Any tips / advice for buying a 2nd hand car in Okinawa?

Hello all,

I've recently moved to Okinawa main island, and plan on buying a 2nd-hand keijidosha to replace the one I'm currently long-term renting here.
I dive and move stuff around, so will most likely be getting a kei-wagon, something like an Daihatsu Hi-Jet or Suzuki Every, which are very common on the island.

However, I've never bought a car, much less a kei, and in Okinawa of all places.
It looks fairly fluid with lots of old, very used cars available in most big cities for quite cheap, Kadena, Yomitan, Chatan and elsewheere. Quite a lot for direct sales as well.

I've been seeing a few ads pop up on local sales groups for keis sold in US dollars (around $1000 US, give or take), but I'm thinking it will probably be cheaper to buy directly in yen (as a side-note, I speak/read Japanese so can also access the local Japanese market, and am not US military).

However, beyond price, what should I definitely look out for when buying a kei here? Mileage, corrosion, tyres, brakes and suspension? Sha-ken status? Any red flags I should be wary of, and traps I shouldn't fall into? How does buying in Okinawa compare to buying say in Kyushu and getting the car on the ferry?

Tips from Okinawa car-savvy users would be very highly appreciated.

cheers!