Where I live, you won't be able to find a mover to transport your mobile home unless you already have the building permit. (The movers can get fined or worse for moving a dwelling without the permits in place.) In order to get the building permit, you have to have a septic tank. The septic tank guys won't install your septic tank (because of risk of fine or loss of license) if you don't already have a septic permit. You could install your own, but you'd still be screwed when it came time to find someone to move your trailer, because you'd be without a building permit.

If I were building a tiny house or converting one out of a shed or something farther back on my property away from the road, I would totally skip the building permits and use composting toilets to avoid the septic issue, because to be honest, the county's pretty lax when it comes to checking up on residential stuff. What they're not lax about is keeping the local tradesmen in line. So since I am moving the home rather than building it, and it will be close to the road, I'll have to go the "official" route.