I did have it with rewards in mind. However, the only thing about it that makes it more exploitable than normal pvp is that the battling player can have less healing cost by bringing only 1 unit, and that you can't be swiped (unlikely to happen anyways if you are fast). If that's a problem, force AP to be in range, but not gear/levels/faction. Then it shouldn't be exploitable anymore, but still easy, fun to set up, and rewarding.
I don't really want 0 rewards for it, but if that's how devs choose to implement it that would still be better than no private pvp at all.