I just had a quick search on Google and there are many removal companies based in Bangkok, catering for international AND domestic moves, nationwide. I doubt you'll find a specialist based in Udon.
I did move up here with a moderate amount of stuff from Phuket. Along with persons returning to Issan and their possessions, it all went on the back of a typical Thai, tarpaulin-covered truck. Very, very reasonable cost. I did my best to pack things well and the more important, delicate stuff (including me and the wife!

) went in our car. No insurance or guarantees etc., but we knew the people were local.
I have seen 'proper' removal company vehicles somewhere. I'm not sure, possibly Pickfords or TNT.