well the akavirii are kinda like the whole south east asia area, many different cultures with many different styles, but a djunke is quite ok i think, but id also check the japanese and korean ships for inspiration, ...and add sails
those ships mostly had rowers for more maneuvarability but also sails for support or prolonged journeys
the imperial fleet of admiral Zheng He which is supposed to have traveleed the world up to south america and back could give alot of inspiration too, lots of awesome ship designs
not sure abut the texture yet, would be nice to see some close up screenshots, maybe even a render, and a model view with the topology/edges visible so we can give more tips
if you wanna use i ingame i also suggest to split the exterior from the interior and delte the other side... kinda like the buildings in skyrim/fallout/oblivion/etc, in exteriors you just see the exterior and once you activate a door you get inside
saves alot of performance which you can put into details or better textures... details!!! lots of em
for example check how they jointed the wooden planks and so on and either put it into your textures or if they have a visible shape that aint fakeable in 2d then model em
........anyway, love the whole idea so far
i just dont fancy the huge rudderwheel thing, that feels too much like a mississipi cruise imo even tho they might have had it, but well, maybe i just need convincing