Cut off those tips, it doesn't get any simpler than that. My CG is at 165mm back has been since day 1.

I had the wingtips on for the first...30 flights. The I bought a Katana P and have not flown my Bad Boy since June 2006 until this past Sunday..after I cut the wingtips off (and I'm not one to leave planes at home for long)

The plane is a totally different machine now. It used to have wing rock like you would not beleive and never had that "locked in" feeling in any high alpha like my Katana does.

Without the wingtips it will harrier with very minimal wing rock (still not as little as my Kat) and the hovers have a much more controllable and locked in feeling. It will actually flatspin properly now too, almost push into a climbing flatspin.

Now I will actually have to make a concious thought about which plane to take to the field, have to stop instinctively grabbing the Kat

I wouldnt bother messing around with the CG and annoying computer mixes to try and fix it, set your CG a small amount aft of reccomended cut the tips off and thats it.

EDIT: That is my V1 in my avatar which now resides in the roofspace it has served me well...the V2 is the plane I was referring to.