If you want HUGE.. get the Sig Kadet Sr. 78 inch span.[X(] And makes the Telemaster look like a racer if you keep it light. The kit version I have seen flown on a .25 and it did just fine. This plane can handle having a .60 put in it and you can pt barn door ailerons and flaps in the wings relatively easilly. (It can do a 0 roll-out landing in 10 mph wind with a .40)

There is an ARF version of the Kadet Sr and they recommend a .46 as best engine when using it as a trainer. You can stick a .60 in and its still good as a trainer, but can double as a glider tow-plane. (and do a lot of other interresting things.)