clikrf8,
If you're looking for a used Hallmark, be extra careful and examine anything 2006 or older. I bought my 2006 used and it appeared the roof seams and around the vents were well sealed. My wife and I used it for a couple of years when I discovered one of the jacks was loose. Upon a closer look, it appears that the roof had leaked and rotted the wood sandwiched between the panels. We were sick because we paid a fair price.
Another problem that developed is apparently the weight of the air conditioner has now sagged the roof and water pools right in the center around the air conditioner.
I called Hallmark and they said "yes" we had a problem, and corrected it with a newly designed one piece carbon fiber roof. I asked what could be done with mine...About $7000 for a new roof!!! Heck, I could have bought something a lot nicer for that kind of total investment.
Now I have a truck camper that I got to keep stored inside to keep it from rotting into the ground. A camper only 6 years old, stored when not used, inside for the last three years, its a shame.