Check with your current auto insurance. Most allow purchase of a vehicle to be covered for a set number of days, mine is 10 days. The state you live in or purchase from will usually have a temporary movement permit available, typically for 30 days. My state will not issue one of those unless you have the paperwork in hand saying you did purchase the vehicle. Some other states do not have that restriction.
Some states will allow you to drive on just the title, no registration for a few days when newly purchasing. If it were me, I would make sure I have an insurance policy specifically for the bus, and not worry about having tags as long as I had current dated purchase info. With Covid complications, lots of DMV offices are not doing business as usual, and cops know it so they aren't being too difficult about non registration.