It had better be an absolutely perfect T-28. You should also be able to prove that a T-28 is suitable for parachuting from. It would help if you could show evidence that it had been done by others many times in the past. The lawyers will not much care about the motivation behind the jump unless they can prove recklessness on the pilots and owners part.
Say, if you fire up your lawnmower, do you go through the same mental masturbation ?
Yes, there is litigation around skydiving, 99% of which deals either with tandem students or AFF students. Rarely, accidents of experienced skydivers lead to litigation and if they do, they don't usually go far. Every time you pack your chute, the last panel you see before you stick the sucker into the deployment bag has a big orange placard:
'Skydiving is an inherently dangerous activity that may end in serious injury or death. The uninsured Relative Workshop, Inc'.
It is the cases of people brought in by a flyer in the hotel lobby and are taken up in a tandem rig and break an ankle in a gopher-hole that go to litigation. Not the experienced skydiver who, knowing the risks, jumps out of a biplane, balloon or from the tail of a Beech 18.
I have jumped out of a 727 and from the rails of a Bell412, yes, both times gosh, I could have died.
The only insurance concern I would have is if the skydiver pulls the canopy off its rails, tears my upholstery or scratches my paintjob. The more responsible skydivers carry insurance, e.g. through USPA for that risk.
Stick to whatever part105 prescribes, do it at a NOTAM'd dropzone, make the agreed upon radio calls, don't launch through clouds and don't f### up.