Thanks for above, re import duties, I should be ok as I am a returning resident. so I can import my household goods (including vehicle) without duties, VAT etc.
I've asked a specialist import company and they can do the necessary testing etc so I think that's ok
Good point on the tint, I'll need to check that, but I guess that may be part of the tests
For Thailand, you need to de-register the vehicle, but that's it
Cheers