Re: Floor Insulation - New Truck Build 92' P30
I would think that the plywood needs to be secured. The only problem with insulating the floor is the insulation compressing over time where you have the equipment and down the isle where you walk, resulting in an uneven floor.
I was in a cold zone, snow, ice, sub zero winters and do not have an insulated floor.
I assume your fresh water will be inside and waste under the truck. I ran a small space heater inside at night to keep things fluid and have a rv tank heater on the waste tank, wrap any other exposed plumbing with heat tape.
Do not close your dump valve, if it freezes, you will never get it open. I have a cap on the 3" dump valve that has a garden hose fitting with a screw on cap, drain from there. If it does freeze you can remove the cap and chisel out the ice. The water will be warm behind the valve from the tank blanket.