Once something is severely damaged it seldom is ever the same again. Seems like the item is forever nickel and diming a person to death in small repairs.
Carfax will only show service that has been done and REPORTED. Many shops do not report repairs because of that very reason.
The best thing to do is take it to a qualified RV place and spend the money for them to go over it. I'm sure you'll get your moneys worth regardless of the outcome.
On edit: the rig might have been used to get out of town. Is just one of many scenarios.