wtf is "to brown nose somebody"? help a non-native english user here, would you, pretty please?
um, just put the raft on top of the cart - a cart has no roof or anything. no need to get worked up

I'm just thinking green and don't want people to cut wood for rafts at every river like no tomorrow.
although fitting many carts on a small raft ain't working then. my bad

a raft of 3x3 would then fit a single cart of 2x2, 2 cows 2x1 each and the ferryman. (or 2 chests and 1 cow etc.)
also I'm not sure if there are any large inhabited islands out there, but just being able to get a cow over a river would be great.
I'm usually thinking of a barge as

, but google says

is also a barge (I'd call that a pontoon).
"Если не я за себя - то кто за меня? Но если я лишь за себя - то что я? И когда, если не сейчас?" Хиллель Старший.