I replied to Leo by email, but for anyone else who's interested, the cottage owners are adamant about not overcrowding the cottage.
The maximum number of people in the cottage is 6, and 3 of those spots are already accounted for. I could potentially shuffle people around and get three more spots
(edit: instead of the two spots I mentioned above), but that would entail you paying half of the rental fee (instead of the 1/3 in my original post), since you'd be getting half of the spots.
So... back to the question: there'd be no point to bringing a cot, since we can't go over the number of people that we have proper beds for.
If you need space for a whole bunch of people, try giving the Lodge a call; they still had a couple cottages free last time I talked to them. If you don't have enough people to warrant a whole cottage, drop me a line instead.