Carrying a heavy spare wheel with tire loose in the cargo compartment may not be save in the event of an accident. Best to have a secure mount for the spare. We're lucky that our 2004 rig came with spare wheel and tire mounted in the cargo bay.
You need a heavy duty jack and wheel nut removal wrench with an extension pipe for leverage plus knowledge about safe use jacks on the side of the road. There is also danger of being rear-ended. If you are not strong enough to handle, remove, and replace RV tires
safely, better leave it to an emergency road service.