Ok so i´m loving my great planes extra 300 sp...

I´m trying to play with the C/G a little. I currently have it stated at the manuals recomended starting point.

Now here is where it gets complicted (for me).
I KNOW that you always set C/G with an empty tank but I just CANT get anything "3d" out of this plane, its far more pattern-like.
Would it be better to set C/G with the tank just half full? As lets behonest, I set the C/G (empty), fill the tank and in a 15min flight, from full am using about 20% of the tank only with the os55ax, so i´m still flying & landing WELL stocked with fuel... ie nose heavy.

ALso, what I really dont understand, like I say I want to move the C/G farther back as I am now very competent with the plane and would like to get it more into a 3d role...
TOday I added some weight behind the wing and moved the C/G from the "starting point" to half way towards the manuals farthest rearward point.
The effect in the air, well I didnt notice any really.. but .. Landing.. the damn thing became a "floater" and it took me about 5 attempts to get it down onto our very short runway. I always thought this was more indacitive of a plane that is NOSE heavy, not tail heavy???

Can someone give me some insight as to what is going on?