In California if you inform them before the registration expires, there is no late penalty, and you pay a non-op fee of say $5 or $15 per year to keep the vehicle not operating status for a while. But if you forget to send them the money before the registration expired, then there is a 10% penalty, and no way to change it to non-op later. By moving out of state, or selling the vehicle, the next owner does not need to pay any back fees, if they did not operate the vehicle on the roadways without current registration. However if caught moving the vehicle with expired tags, they will bill you as though you had operated it every day for the past years. You can buy a permit for moving a vehicle with expired tags, or dealerships have special license plates to move un-registered vehicles, that they use all the time. If a gas vehicle that needs a smog certificate, you might need a trip permit to move it to a facility to get it a smog check.
For some states, they require the payment for trailers because in theory you could have been living in it while not moved around on state roadways. But motorhomes are treated different, and are allowed to be non-op for a few years.
You will have to call your department of motor vehicles, and ask. Have your license plate number, ect. and they can tell you what you will need to pay to get it up to date.
I have heard of a 1974 travel trailer moved to a camping resort, then parked in the camping resort's storage area when not being camped in. The owners left it on the property for years, and never took it out on a highway, even keeping the original 30 something old tires. When they went to sell it, it became something of a problem, as the California DMV did not have any records from 1974 of who owned it, or if they could sell it. Basically they had no title for the vehicle because it did not have non-op status or any registration for a 10 year long period, and was 'dropped off the books' as though it had been scrapped and nobody told the DMV. By that time the 30 year old camper had seen better days, and was scrapped anyway, as registering it would have been somewhat of a nightmare talking to the DMV.
Good luck,
Fred.