We feel your pain.
The heat will evaporate the water in your toilet. Butter the toilet ball gasket with a thin layer of silicon grease (leslie's pool supply has the best we've found for this.) We like to flush our grey & black tanks well, then leave them about half full with a generous dose of bio enzyme (Rid-X, etc).
Leave a pan of water in your kitchen sink, another in your bathroom sink for humidity. Your cabinetry will thank you.
If you have vent covers and screens on your ceiling vents, bath and elsewhere, leave them open for ventilation. As we moor our rig next to our house and have 50amp available, we allow the ceiling vent fan in the front room to run 24/7. Our fan is original to our rig and hasn't complained a bit. (About the only time that fan is not running is when we are rolling.) Even if it should burn out, we see replacing it as cheap insurance for the benefit provided,
Make sure your ports for water, electric, sewer and any other are closed. Survey any other rodent access and plug with steel wool.
Leave NO food in the rig. Rodents. Rodents.
If you are not leaving the rig plugged into shore power, isolate your house batteries. Also your chassis batteries.
We like to extend our leveling jacks enough to take most of the load off the tires.
Embrace the heat. Remember, it protects us from the out of state riff-raff.