You will be limited in your choices of sites. With a 38' trailer and full-size pickup, you will be 58-60' total.
In your shoes, I would look for a shorter trailer, unless you are willing to accept limited choices of sites.
Some sites you will have enough length for the trailer, and then can un-hook and park the truck beside the trailer, or angled in.
IMHO your biggest issue is going to be bathroom accessibility, if your wife is using a walker or wheelchair. Most RV bathroom doors are too narrow for either one. So take a hard look at the bathroom layout.
Single empty-nester in Middle TN, sometimes with a friend or grandchild on board