I think my situation is similar to yours: I have a boat trailer that was previously registered in NC. I actually still have the expired tag. The trailer sits at my home and since I have a boat ramp I do not drive it on the road. I still have the old tag but have not renewed it in years. I get no notices for taxes or registration from the State of NC. Of course it would be illegal to put it on the road, but as long as it is not on the road I think I am ok. When / if you go to register and tag it again be sure they understand it has not been driven on the highway. You could call DMV and verify but I think this is correct. Don't know if you would have to pay back personal property taxes because in NC they are now tied in with DMV registration.