I like the idea of the roll cage that disappears into the roof behind the drivers head onto an internal hoop arrangement.
so the plan is 3 sets verticals down to the chassis!
a: outside at the windscreen down through the wings onto the chassis
b: inside behind the seats down to the chassis
c: inside in the back by the back door down to the chassis at rear crossmember
b+c are connected inside by diagonal and verticals