The Reg White Tornado's that I have experience with, used some type of alloy plate, glassed into the hull. It would be unusual to use a stainless plate on a Tornado. The extra weight of stainless could be better used somewhere else and it's easier to fix stripped threads than galled stainless on stainless(broken bolt, twisted plate,...).

I have tried all of the fixes in this thread (and couple of others that were really bad ideas) and my preference is heli-coil. I have had no problems with my heli-coil inserts. Be sure to use the correct insert. Inserts into aluminum alloy are normally coated and may require an adhesive or primer. On the recommendation of a friend, I bought some at a motorcycle shop and was told "This is the best kit, it's made for a jet ski". The inserts are black coated and I am guessing they are heli-coil Primer-Free. One big advantage of a heli-coil is, you can remove them and put is a new one. I suspect a heli-coil will outlast my hulls.

No matter what you use, use anti-seize on your bolts