If i were to build a tiny home on wheels, and park it in the back yard of my property, would i have to pay property tax or any other fine in order to keep and live in the tiny house on wheels?

What if I were to register it as an RV? Or an adu?

That would be considered a mobile home and in Kaufman County until they see it and catch it you probably wouldn't. However when they do and they find out how long it's been there they can back tax you.

Im pretty sure not if you are outside of any city limits. However you would need to permit your septic system.