this is poorly written, and not to well thought out...
i'd think making it easier to capture a base (or easier capture with even easier recapture) would work better than harder...hell, it might even lead to a more realistic use of heavy bombers. worth a shot anyway, since every attempt at making things harder to fix problems seems to just make it worse.
the base is already captured by the time slower half of the horde arrives, hordes need not be so big (or present at all, why send 20 planes when 10 will do).
if the horde moves as a single horde, by the time it captures the other team could have recaptured behind it...they'd have to leave some people behind to properly defend the base, or at least launch an attack on more than one base at once, splitting the horde.
it would be chaotic land trading with no-one getting anywhere for a couple weeks sure...but end result would be
the horde shrinks from one big horde, into a bunch of smaller hordes...the smaller hordes would be of lower numbers, that furball types could baby seal club, without being overwhelmed...
result being
the horde trys sending more people...but again, then they cant take and hold enough land if there wasting people...so they pretty much have to learn how to survive interception, either by hiding in groups of well armed bombers, and/or bringing a couple guys who can fight a bit to come and help them, and/or getting a bit of fighting skills themselves.
some discover they like fighting better than base capture, start exclusivly escorting or intercepting...then starts looking for furballs, or creates some when the escorted are dead, and the escorts are still alive.