I tow with my 95 Exploder all the time. It has well over 200K, likely 300K (odo broke several years ago at 189K). I will add that, I am ridiculously meticulous about maintenance. This one is showing it age, and the engine is not as strong as it used to be, but I use the heck out it. Not sure I would just drive it cross country with the camper, but if I needed to I would feel comfortable doing it.
"how old is too old" depends a lot on the owner of the TV. I have been in some 10 year old vehicles I would not drive to the local walmart, I have been in some 30 year old vehicles I would drive cross country in.