This whole thing is sad, and we all feel a sadness for you and your son. I think you have to make a value judgement on several issues that we on the forum cannot make for you. All this being said it seems to me that if you have seatbelts, talk to your lawyer, and decide it is OK, then do it. One other safety thought, if you think you need it, is a roll bar. I've helped rebuild a TR6 for my college age son the last 5 yrs and his Mom insist on a roll bar before we got very far along. It seemed a good idea to me.