You've done a good job there. I'm afraid I'm not aware of anything particularly useful for this. Maybe other LAFers know better. It had been something of a sticking point for me with canoes, as I really can't be bothered to go through such conversions as you have for figures that will see such little use.
Therefore I had resolved to simply use whatever tribal figures I happened to be using in their normal standing poses. There is at least, some historical precedent for this, as in these silly buggers displaying a scant regard for health and safety, whilst also doing their best
George Washington crossing the Delaware impersonation (whenever I'm in a rowing boat I always race to claim that spot in the bow to avoid any actual rowing, and strike up a suitably dramatic pose. It has only resulted in my falling in the river a few times):

Might be a way to at least cut down your workload, by having some of the occupants standing up and waving their arms about instead of behaving sensibly and helping with the rowing.