I’m 71. We carry two bikes in the covered bed of our pickup, one cruiser for my wife, and a full-suspension mountain bike for me. We have carried them in the Airstream, but too much dirt gets tracked in.
Bike suspension on an off-road bike is a back saver, and greatly helps maintain control in descents.
Our bikes have flat pedals, i.e., the kind that have screw-in studs to give you great traction on your shoes. Clipless pedals are not required, even in the most rugged, mountainous terrain, and you can wear the same shoes to drive the car, go to the store, work around camp, etc. My shoes for riding and all around (but not good for running or hikes) are made by 5/10, a company that specializes in mountain climbing footwear. Good stuff.
Going seriously off-road is great if you have the experience, strength and skill to do the job. So equipped, accidents seldom happen and, if one occurs, you have already learned how to fall without injury. If you are relatively inexperienced in the world of mountain biking, riding alone in some of the country’s mountainous trails can be ill-advised. Stick to easier trails while you learn.
Riding shorts and jerseys are designed for the activity, and serious rides are comfortable with them. Jeans and T shirts are fine to ride to the showers or camp store.
Cycling gloves and helmet are a must. If you take a tumble, you generally will land on your head or hands, and, if you’re lucky, your feet.
And my wife and I wear RoadIDs when riding. Cheap insurance.
https://www.roadid.com/