No doubt there is uncertainty right now and depending on the work you do, to a greater or lesser degree. But things will return to normal eventually.
I also have multiple projects going and when your daily driver is on the "needs attention" list, priorities shift pretty quick.
I figured I would mention the perforated film and at least it could be referenced later in your build thread as "paint" for your truck looks okay even if it isn't the paint you want right now.
I know you are having some engine heat issues even in the winter. Have you been able to check the condition of your radiator, in the photos it looks like a fair amount of paint overspray is on the coils, this could affect heat transfer and even though it is a really low mileage vehicle it is till over 30 years old and the radiator is most likely original. My '86 M1009 only had 42,000 miles on it when I bought it at auction but I had some engine heat issues but didn't have the extra 2000 pounds of ambulance body to haul around. It was pricey but having the radiator re-cored made a huge difference. Pulling long grades in the summer in Southern California would make the engine temp light flicker and the fan clutch would lock up so the engine fan would roar, I would back off the throttle to help it and the light would stay off for awhile. After the radiator re-core with the thickest core that would fit the tanks, I have never seen the engine temp light again except for a moment when starting so I know it still works. Since moving to Washington, it takes a bit to warm up and I need to get a cover for the radiator so it warms up faster. Mind you, where I am just north of Portland, winters are not really severe and looking at the pictures you have posted of your winter trips indicate it is most likely not as cold normally for me. Anyway, just another thought to consider, could be a very straight forward solution. I had originally thought I only needed to have the radiator rodded out but the shop called me and said the core was shot and would need to be re-cored which kind of surprised me since it didn't leak that I was aware of.