(not done any mesh for a while (like a year or two)) But, i assume it would depend how the pysical type (convex hull, prim etc) was setup and if custom psyical mesh was made. But, it is do able.I don't know how hard it would be to keep the 1prim limit, as the prim weighting has all changed. but i think should be able to pretty easy. (was from what i remember a few year or so ago though). With mesh you can build your own psyical shapes etc. so dont have to be constrained by bounding box, but, they cost more LI weight, so more prims.
C# would be vastly better than lsl in so many ways. You make it sound like using c# as the scripting lang would be rocket science. But truth is it would be just as simple or complex as you want it to be. So script would just be like in lsl .. touch action > light on > done . No complicated classes needed or pre thinking. It would all be same just different syntax, But at the same the same time access to a lot more power. Also there is big difference between script and a program. The ramp to learn to write a c# script would be same as it would be learn lsl. Would not be that many differences.