Replacement of all the tires is a must as it does not matter if it was towed or sat they start to deteriorate as soon as they are made (per tire manufacturers own statements) and have a life of 6 years from date of manufacture.. As for the roof coating every year...why? It is totally out of the norm to do that....was she just sold a bill of goods by the campground or service company? Just sitting in the sun does not mean it will go bad. Problems arise from lack of maintenance and mainly the roof causing leaks. Be aware that you will need to have a good habit of checking the roof for cracking at vents etc since the unit will now experience flexing it has not had in years. Sunnybrooks back then were well built and better then average but not high end (sorry). Other potential problems are the electric jacks and other items that have sat unused for a long time. Buyer beware and ready for repairs.