Hmmm, I was reading about taking pictures from planes and most recommended a
300mm lens..

crab the plane to get the wing up out of the way for photos, but you don't
have
much left rudder available. Plan on no more than half an hour of shooting
before
your left leg gives out. I would avoid using lens larger than about 100mm
unless
you have one of those gyroscopically stabilized units.

Real good idea!

I would recommend using a good camera strap, just in case.