I think you’re getting overly concerned about this for no real reason. Noticing it is good, but there’s no need to worry.Cold, rear is at 46 and front is at 53, I’ll keep you posted. The front obviously with the weight of the engine has a good contact patch.
When our rigs are empty back there, they’re basically just floating across the pavement.
This is where tire rotation is key—swap those fronts every 5K~ miles and the wear should even out due to the engine weight as you mentioned.
Toyo's are generally made out of a harder rubber compound, but once the rears are moved up front, they’ll start rounding out those outer edges and vice versa.
I run Toyos on another SD and have noticed that no matter how low I go, they still wear flat when empty, but that’s the beauty of rotation—they balance out once moved to the back.
As already warned, be cautious when running tire pressure too low if you’re towing; keep those pressures appropriate for the application.

