I don't know if the RV-7 leg is similiar to the RV-10? With the 10 gear leg, the gear is predrilled. The mount has one hole drilled just undersized. If you made it through the undersized hole and were drilling the opposite side and the bit broke as it was breaking through, try a small punch from the breaking through side to punch the piece of the bit back out. If it was not about to break through, you could try drilling a very small hole (sized for a small punch) as centered a possible to where the hole should be and punching the bit out through that hole. If you broke the bit in the undersized hole , any chance you could punch it into the gear tube, then remove the leg to get the bit out?
Ron