It is important to have MSO/MCO from the manufacturer even if you don't have to title/register it in your state. Ever since states have required titles, manufacturers were responsible in creating these documents for their products. It may be that the original dealer or buyer threw those out?
https://en.wikipedia.org/wiki/Manufacturer%27s_Certificate_of_Origin It will make a sale easier to someone that does and hopefully you get better resale at that time. In my state, the camper is titled and plated. The plate pays for public dump stations that do not have additional fees, so I am willing to pay the registration on the camper. It also exempts my truck from some commercial restrictions due to it's exclusive RV use. If they offered me nothing in exchange, I would be looking at a camper as cargo and pushing this as far as it had to go make a change.
I have gone through lost title and never registered vehicles in my state also. My experience mirrored yours except for the wait. If you have documentation like a MSO/MCO, you can get a title within a month. If the paper trail cannot be linked back through previous owners to the manufacturer, you get a provisional title for three years before you can request a permanent one. The amount of time I have to spend to do this with possibility the vehicle/camper is stolen and gets confiscated makes this type of buy only attractive to me at a bargain price. If the seller wants the sale that bad, he can do the foot work and get it titled so I can pay closer to market value.