As a newbie, if you don't have a very experienced friend to go along (and even then, they make talk a better game than reality), once you are ready to make an offer, include a requirement that it pass an inspection, then pay a mobile RV tech a couple hundred to give it a good once over. Make sure it includes operating every system.
Assuming, the seller still has the truck to pull it, consider including a swing by a local CAT scale and plugging in at an RV park with 50amp outlet for the inspection (at your cost of course)
Also, as someone else mentioned, make sure you have enough truck. A 41ft 5er can easily have 4-5,000lb pin weight, so even if the truck has sufficient tow rating, it may overload the truck. Assuming 25% of the GVWR as the pin weight to be on the safe side and don't forget to include the weight of the hitch, people and any other cargo in the truck.