RE: TT .61 pRO ON A AVISTAR !?!?!?
It would work. I don't think any additional support would be required. It would be better if you looked into a 60 size trainer to begin with, Easier to see, easier to fly, easier to learn. The difference in cost isn't really very much if you are already investing in the 60.
If you go the Avistar route, remember not to use all the throttle available. Yea, right.