While i can see were the concern is, i disagree that its a problem. Active players/tribes should be rewarded over semi to non active players.
A counter argument is we can already today monopolize resources though totems and denial of access.
if a 80 member tribe decided to setup on a scrap pile you can't pull resources or cut down trees, plain and simple.
Personally, i do not have a problem with that. But I think is see some potential for what Ooloo is concerned with, i'd be in your shoes.
The solution to this is:
-Make whatever bonuses apply to a zone apply to everyone while its in conflict. Then while the defenders and attackers are busy with each other. Every other player that has no interest in capturing the zone can rush in and pick and harvest till the zone is no longer contested(or until what ever upkeep is paid runs out). This would add another element that would require the defenders to choose between defending the capture points or denial of access.
Then people even people that have no intention of capturing the zone still have something to win by attending and generally causing havoc. Yes you would get squatters that camp out on the edge of the zone, but i imagine that the neighboring zones would be medium danger. Implying that pvp would be active in those all the time.