i think the solution is to have the one queue feed into all castles of that time limit, that would then move four times as fast and stop one person taking all castles in a particular time limit (imagine edmond dantes holding them all!).
i think the queue should also be trimmed to a shorter length, 10 or 15 people say.
regarding castles of different ratings - tournaments sometimes do this, and someone with a temporarily low rating clobbers everyone else - it needs to be that entrants must never ever have had a rating higher than the limit (provisional ratings not counting of course, because they fluctuate so wildly), then the issue will crop up of someone who improves ??? i am not sure how to deal with that.
ps 35 games will take a lot lot lot longer than 4 months, 4 years is more likely.