Salt Lake to Albuquerque on a 40 Pusher then to Florida.

Just plan on fueling in the towns -- Monticello, Cortez, and Shiprock. My preference would then be 491 down to Gallup, as 550 is a lot more remote. But all of them are quite safe in my opinion.
Moreover, if you have some sort of problem, the folks in Navajo Nation will be more helpful than on the rest of your trip.
Things are buttoned up there, though, as they've had a rough go with the virus.