Well...after 150,000 miles
Well...after 150,000 miles you can expect to find at least some issues that may need taking care of just because of aging alone. For example, if I had the same vehicle and were planning a trip towing a camper, as a minimum for safety's sake for towing I would make sure the suspension is good and the protective rubber boots covering all joints and the axles were not rotted off or seriously cracked open. Since towing puts a lot of stress on a transmission, you need to find out if the fluid has ever been changed. Have the wheel bearings checked along with the brakes. Tires should be relatively new---you do not want a blowout while pulling something. Find a mechanic you trust and ask them to give it a once-over is best. And most important of all---make sure you are not exceeding the vehicle's towing capacity, which is one of the biggest mistakes towing drivers make.