I'm not surprised they are being reasonable about this. These rules weren't made up by the motor vehicle departments to hassle people and make work for themselves. The federal government forced this on the states.
I'm doing something similar. I'm renting a very small outbuilding of a two apartment unit and then sub leasing it back to the tenants in the main unit so they can have easy access to the washer and dryer and a guest room. I'll have the lease to show the DMV and it will be no different than if I rented a home I owned or an apartment I leased and went away for a year which people do all the time.