The spare wheel in our Tioga 26Q is mounted in the front of our cavernous cargo hold. At age 82, with "issues", I might be able to slowly remove all the stuff to clear access to the spare but would not be able to crawl in, dismount, and get the heavy spare wheel/tire out, much less get the rig jacked up safely and remove outer and inner rear dual wheel and mount the spare on the side of the highway.
I don't like to think about a tire failure underway but carry AAA emergency road service. Know your limits. At least have a usable spare aboard.