I do not think that it is attractive enough for manufacturers to homologate a car that fights only for a class win or drivers that is driving just for fun. I believe that a RGT car would be much more expensive compared to R2 and R3 so there wouldn’t be a big market for them. If they had a own championship it could be different (RGT ERC).

Btw, it would intetersting to know which countries have a class or championship for GT cars and what kind of rules are in use.