This is the most reasonable way to do it. The general problem with grapple is the limited scope of actions which means that...well, almost every class ability and monster ability is unusable there. Also, they botched up Grapple-check definitions something severe.
Like, technically you should be able to PA up to your BAB without any penalties on your Grapple-check and deal the boosted UA damage, because yeah, Grapple-checks supposedly aren't attack rolls. This is why I suggest heavy handwaving and houseruling on the fly whenever grappling - go with what seems to be the most sensible thing.