I'm at 10 years and see no reason to not go another 10 or more. How do you check a RV roof AC? There are no test ports to check pressures like on a home unit. They'll check the box as OK when it works... pretty sure I can do the same for a lot less. I'd probably spend some money on spare parts like start capacitors, a spare thermistor and ignitor for the refer, and other items that are critical.
I'd do oil sampling on the engine and tranny to establish a base line. I'd replace the serpentine belt and keep the old one as a spare. At 7 years most will say you need new tires although I went 10 on my rear tires.