Well, IMO, rcworld2000, you should FIRE your Trainer. In any situation of the normal airplane configuration, that is, a prop up front or a jet engine just aft of the wing center, and will be flying within the realm of convergent-airflow (sub-sonic) 25% of CG is an excellent starting place to obtain great flying stability. Of course once you get use to the machine, then one can generally be safe by making some changes and just seeing how far you can go with those changes. Your airplane -- treat it as you wish. Now as a student and you have denied one of the best-ever RC pilots, that is telling you the basic aeronautical truths, well keep your glue and stuff handy. You will need a lot of it.
Differential aileron is absolutely a great thing - I would never be without it in sport, especially Scale models - but, big daddy, it ain't gonna solve your CG problem. I have a 100" gasburner Eindecker. I fly it at Big Bird and sport-scale events. The plans called for a 33-35% CG point. I knew that was wrong but I went with the .33. My first flight looked like I was trying to do 3G. I managed to recover and added lead to get 28%. Still bad flier. Then I added more lead. 25% cg. FLIES SO SMOOTH. Take-Offs and landings are sooo easy. Been that way for about 4-5 years now. OK, Captain rcw..., it's all yours, I am Ba-i-l-in--g... O-u---t..t!