Only the real high-brow, uppity, nose-in-the-air Private (expensive) RV Parks have an RV age requirement. A federally run campground will not discriminate like this.
Take advantage of the fact you've decided on a Fifth Wheel. Get the biggest and best 5er to live in a proper two vehicle (don't underestimate this!), then set up in the larger resorts outside the NAT Parks and drive in to see what you want to see. You'll save money not having to locate suitable site where some tree or tight turn will cause a problem (no dings, no dents, no broken trees or feelings). Most Parks have 22-24 ft limits and if you're like most retirees you are looking for comfort versus being cramped.
I have a 38' 5er and have been to Sequoia, Yosemite, Mammoth and not had any problems finding a place to set up, but I would not even try to fit into a Nat Park's primitive campground. First, it's not considerate to others (blocking out their sun, view etc.) and second, I don't like having to shoehorn into a site. RVs take up more space than they used to with slides, the tow vehicles, all the junk you can bring along, etc.
There's a lot more to discuss but requires much more information such as:
- Mental state: do you consider yourself a visitor or do you think you deserve to be there.
- Do you have to have all the comforts?
- How much do you care about others?
- How handy are you?
- How are your driving/towing skills?
Don't take this lightly. This might not make too much sense until you hear all the answers for each.
