The first most important thing is to check the roof and especially the radius on the sides where the roof tucks into the drip rail. This is vital. YouTube channel AZ EXPERT has many videos about the topic.
Short version, if the sealant fails there due to age and UV there is nothing holding the roof down and you can lose parts of roof while driving. The roof is one piece fiberglass reinforced plastic… Filon brand… it is not regular fiberglass like a boat or the caps on the front or rear of the RV. It’s thin and can tear.
A thorough roof inspection is mandatory before purchasing.
One other thing, when built, the factory used a silicone caulking on every roof mounted item. It’s good and lasts a long time. But nothing will stick to it except a silicone caulking. So if previous owners ever recaulked anything up there with Dicor or similar caulk it may appear good but you can pull it right off.
So,be aware that you need to use only a silicone caulk (NuFlex 311 or Huangs 311 or other) roof sealant in the future. Geocell ProFlex is used on that roof radius at the drip rail that I mentioned above.
It’s a great coach, enjoy!