Idaho lets you plate them as ATV/UTVs and you can't drive them on the state highways.  But city, county, and Forest Service roads are fine.  Most of the time, I use it to put around town, or at my place.  I can get to most places I go without being on a highway.  So, it not being highway legal hasn't been an issue.  Insurance was pretty easy once I figured out how to pad the serial number into what would be a valid VIN. 
That said, I made a run to the dump with mine, which required about 4-miles of US93.  Had the utility trailer full of yard waste, and the truck full of collapsed cardboard boxes.  Slight grade the whole way, so couldn't get above 45-mph, and turned on the flashers and the rear hazard bar.  Highway patrol came up behind me and followed me to the turn off to the dump and turned after me.  As soon as I cleared the turn, he hit the lights.   I figured I was going to get ticketed.  He walked around the truck and looked it over.  Then said, "Its safe, stupid law.  So, have a nice day."  Got back in his car and left.  The County and City guys would never bother with a ticket.