Terms searched: keelboat, narrowboat, passenger(s)
1) There are mutant hybrids of barges and keelboats/narrowboats (probably best to think of it as an overgrown narrowboat) that are towed along a large river (bigger ones may be poled, further towards the middle; barges and boats come downstream on the current). This one is being towed along a towpath by oxen (I think the path is to the ship's left/portside). It is in use to haul crates of "exotic" fruit from Port Town A, upriver, to Capitol Town B.
2) The configuration that seems plausible is to have the crew cabin at the back; the person at the rudder is on top of it/part inside it. The cargo runs down the middle, with tarp over it. Crew will be keeping an eye out for would-be thieves (rare in this area, but not unknown), watching for debris in their path, and poking the boat away from the shore (presumably).
3) The two protagonists (teenagers) have acquired paid passage on this thing, even though it's "cargo season" and it's not set up for passengers.
Question: Where the heck do they park themselves in this situation, that will be out of the way of the crew? Rear starboard corner near the crew cabin? Should there be space in the bow for them?
It's an effin' throwaway paragraph, practically, to stick them somewhere so they can start talking and have some character and relationship development, but I can't figure out if I'm right, or if the cabin should logically go all the way across (so there is no spot there to put them) or what.