With Tranio up in the crow's nest he is not able helpfully to take part in the discussion of where to land.
Since the ship has a balloon and pontoons, landing somewhere North of the riverboat makes sense. Normally I'd think landing (covertly) on land, disembarking but leaving 2, and then taking off again makes the most sense.
Then people can just get on at the next stop, and we keep our means of transport. Im not normally one to split the party, but unless we're going to give up the airship (or are prepared to abandon it) I don't see an alternative.
Tranio is not skilled in relevant abilities, but is willing to be one of the two if this makes sense.
I was thinking we land in the river and approach the casino head-on, but then I think maybe Aremus read too many pirate novellas. (Not that he would advocate violently boarding them... unless they resist!)