I wouldn't bother including two RST reports. I've never even seen that done, that I can recall, and there's no purpose to it.
I would include grid square and CQ zone at least, maybe ITU zone also if there's room.
For those designs that don't have your address data on the "front" (picture) side, I assume it's on the back where we can't see it; make sure that information is "up high" on the card, well to the left side, to prevent it being overmarked by the post office bar code and stamp cancellation marks which can completely obliterate stuff printed on the "stamp" side of the card (if you ever mail cards not protected by envelopes).
A government which robs Peter to pay Paul can always depend on the support of Paul.
-- George Bernard Shaw