Well, any victory on "no man's land" will give corpse looting privileges to the victorious army (which concerns me a bit too for the reasons Darwin stated) but I expect the defending player will have dibs on any carcases that end up in the shadow his stronghold walls. So, if an attacker is careless he might end up "supplying" the defender with resources. One potential problem I see is if the defender ends up pinned inside the castle unable to loot before the next wave arrives. This depends on whether army camps can train new soldiers (I read ships will be able to do it) or does the attacker have to bring his units all the way from his stronghold.
It might be nice if any such non-stronghold "forward bases" that are able to build units did it at a slower rate than the stronghold which would allow the defender to recover a bit faster (if he has enough resources of course) than the attacker.
But yeah, don't change corpse looting until we've actually played the game.