When you park that Ford F 450 for the winter, do so with the hood fully up.
If it has an under hood illumination lamp, unplug/disable.
Vehicles with cabin air filters can also benefit from heavy metal screen reinforcement in that location.
Mice can/do chew through cabin air filters for getting inside the vehicle.
Most vehicles with air conditioning also have a cabin air recirculation door. It allows faster/colder cabin air temperatures in extremely hot/humid weather. Be certain (if possible) that the A/C recirculation door is fully closed when parked for the winter. Open, it's easy access for mice to get inside the passenger cabin area. Mice can/will chew through plastic mesh guarding the recirc door, if it even is equipped.
Keeping the A/C recirc door closed with the vehicle off can prove problematic, as the usual default is open unless recirc is activated on the A/C controls head. Disconnect the actuator from the door if needed and if possible without removing the entire dashboard from the vehicle. (some are buried so deeply behind the dashboard, it's impossible to access the recirc door) You might be able to block off the recirc air intake with metalized dryer vent ducting tape if you can't reach the recirc door.
Single battery or dual batteries? Battery tenders as needed. I use Harley Davidson battery tenders on every single piece of equipment here, including my almost daily driver Jeep Wrangler Rubicon.
There are enough H-D battery tenders out in my shop building, that at night in the pitch black, there is a soft green glow in the entire first floor, from the indicator LED's on the tenders.
(two Kubota BX tractors, two motorcycles, one ATV, one side by side, plus the Jeep located at the house)
Go to this website and see/get the plans for building mouse death buckets:
Free plans to make a homemade mouse trap using common household supplies. Includes step-by-step instructions with pictures for easy assembly!
www.trap-anything.com
I routinely have several of these in my barn/shop building all winter long and another in my home.
(in the boiler room)
If you add enough RV antifreeze in the bucket of water, it will not freeze.
Using R/V antifreeze, if a pet finds the mouse death bucket, it won't kill them like ethylene glycol will.
Some add a 1/2 cup of birdseed which will float on the top of the water/antifreeze.
These mouse death buckets do not require very much human interaction.
Each one will trap/kill mice over a period of weeks without you having to reset/rebait.
I use an old pasta kitchen tool for fishing the dead mice out of the liquid in the bucket.
In warm weather, I put the deceased mice out on the old stone wall as offerings for the local wildlife.
In the winter, the mice go in the garbage can.
If you build four death buckets, one on each corner of that truck should adequately protect it.
Good luck with your winter truck storage!
If something looks even remotely useful I have a hard time throwing it away, and today's project only serves to validate that genetic disorder. Earlier in the summer while working on boat upgrades I decided that I didn't like the expanded rubber mat in the center console. I put it on a shelf in the garage thinking that it'd be useful somewhere else. It sure was! 
