Trailer tiny house import Bulgaria

I am interested in companies which are producing trailers for 3,5t which are used for building tiny houses.Also interested in the metal framing for the houses.I know there are also companies that you can order tiny house framing(different models) and trail and they can send the walls and the trailed disassembled in main components so it is easy to transport.This is also an option.
Mainly interested in trailers, which can come in parts and on place to be assembled(easy transport).Already ready trailers would be an option too.The lengths are from 4-8m.They should have all the certificates to be registered in EU.