Aft c.g.s can be tested by diving... if the plane pulls out from a moderate dive, after being trimmed for level flight,
and pushed over, the c.g. can go back a bit.
If the plane doesn't recover, or the dive increases, the c.g. is at the aft limit.
Note this test is speed sensitive... as speed increases in the dive, the plane can increase the dive angle.. another indication the c.g. is at the aft limit.

Now you know why I design my planes with a free moving CG- which can be rolled fore/ aft as needed .
I believe Great Planes or one of the big stores have these in stock------
PS- I think they have these in various colors -

CG may be able to be moved back... I like mine as far back as possible so that the airplane is still controllable with an empty tank... Take your plane up an run the tank through it/put 1/2 a tank in it and take off... run till she is about to dead stick, or untill she does... If it still glides down good you can add more weight... Trust me all competition aerobatic planes/models have their CG at it's aft most position... On the knife edge issues does your wing have any dihedral?? If so it will be a little more difficult to hold knife edge... Her is a pic of my big stik 40... I had it at the recommended CG and wanted to move it back to be more aerobatic... 3 OZ of lead... Fly's great...

That's some serious weight for the tail there Scottfl78. No the wing has no dihedral and the wing is midway in the fuz. I might move the cg back again a little tomorrow... see what happens.

The pitching with rudder is affected by the CG placement.

Making a lot of changes all at once makes it really hard to tell what any one did. Since you seem to be pretty close, I'd make one change at a time from here on out to get a better handle on things.

I did some more flight testing today, Got seven 15 minute flights in and flew the wings off it. It was quite a breezy day again but gave it hell to see what it was capable of. I've realized that some of the changes I made need to be reversed, it is so like the SSE it's unreal. I personally think the worst thing I did to it was give it a longer moment arm, it is too easy to totally stall the elevator and rudder with lots of throw.
I tried adding a little weight to the tail and move the cg further back than 5 in but the plane was not impressed and flew pants. So I must be on the outer edge with the cg already.

Prop hanging is the only thing it seem to do easier and today I could not get one Knife edge out of it, the wings would flick either way with a vengeance... it was just having none of it. I was surprised considering it was no where near this bad the other day.
It is quite erratic on climb out after take off, but when I pull back the power, it's a lot more stable. I run out of fuel on the second flight and yelled dead stick, and was still gliding about for 3 or 4 minutes before it lost height and came in, maybe it's a reincarnated slope soarer.

I agree with the last post, it is not a good idea to make many changes at once but time is a major factor and while the thing is in bits it is easier to do all the changes then re cover.

In my mind I know what I am trying to achieve and I'll know it when I fly it but knowledge is a great thing, if you haven't got that knowledge you can only experiment and learn.
I could spend a great deal of time and money buying and building different kits before I find the one for me, so I guess there is no harm in asking for a little help from those who may have already been there.

What do I alter first? Any suggestions.

Oh, and I forgot to mention, If I let go of the sticks while at low to moderate speed the plane goes into a vertical dive picking up speed all the way, no signs of it pulling out like my PC9. Gives ya brown trousers, enough of that I think.

"...vertical dive..."
That sounds like you're holding elevator for level flight.
A trimmed plane can't know whether your fingers are on the sticks.
In the real world "stick-free" stability is a testing criteria, but with our models, the servo holds the surface so the plane has no genuine "stick-free" mode.
Are your ailerons aligned along the true chord line of the airfoil?
If the aileron trailing edge is down relative to the zero chord, it acts like a flap, which increases the nose-pitch.

Dick, I thought the CG's only came in black and white. The colored one's probably are a modern solid state version. That way you don't have to move it to adjust the CG. The problem I have found is that with a stick fuselage there isn't room for a big CG so you have to use the little ones and they don't work quite as well.

Way back when, Pylonius (in "Model Aircraft") was complaining about c.g.s being wet all the time, as they were consistently located in the fuel tanks of the control-line planes he was flying...

[Yoda voice] Strong is comedy riding in the Force today.... [/Yoda voice]

What a bunch of chameleons....

Stratman, you MUST be able to set the elevator trim for hands off flight for the dive test to mean anything. Having said that it sure sounds like you're on the ragged edge. Flying slower allows the use of very rearward CG's at or even slightly behind the neutral point. Let the speed come up and you've got a Nervous Nellie on your hands. Speed is also the villian when you use 3D type throw angles. Keep it low and the model will be a LOT smoother. If the model speeds up just BREATH on the sticks and no more.

Upping the ration of the exponential settings can help but at the root it sounds like you just need to adjust to the new reality of flying a model of this sort.

And I'm not sure what you meant about the longer tail moment messing up your controls by "stalling" the surfaces but that just can't happen. With the reaward CG and longer moments comes lower efforts for the tail surfaces to achieve the same effect. I think you're seeing something else at work. Perhaps the stronger control effects are confusing you. Looking at movies of 3D models the sudden massive increase in angle of attack that can be generated by the full measure of 3D throws is enough to completley stall and stop forward motion. But this has little to do with stalling the tail surfaces themselves. Even regular model controls are stalled when the angle gets much, if any, over 15 to 20 degrees of deflection. But there IS lift post stall so it doesn't matter as long as the big fan on the front can haul the baggage.

Oh, and a bunch of years ago one of the magazines had an article reviewing and offering to sell stick on CG's so you could put this important item whereever you wanted it without all the pesky nose weight and stuff to mess up your model. I'll leave it up to you guys to guess which month the issue was....

OK- --I guess I better not comment on my 3D CG's - which have a nice rounded look--