@My78truck,
I know a lot of people don't have much luck with spray can paint. I've been using it since the early '70's. I had some good instruction from car painters on how to use it, and including tests with the instructions on the can. Those instructions are for general conditions and can't be relied on in "your results may vary" sort of thing. And I have seen this very thing when humidity is high. I call it "fogging" and it's when water is drawn into the paint as it's drying. And it's true that the driers in the paint can are the cause of it. But when it says temp. 70 and humidity at 55 you've got to get as close to that as possible. You can go higher with the temp. but not so higher with the humidity, maybe 65 percent.
But here's the deal once the water is in there you will need to remove the paint down to the layer that is affected, and under as best conditions as there can be, then spray. If it fogs again, it's deeper and you'll have to take the paint down past that layer. I know that's not what you want to hear but unless you can find someone who has a booth
you may have to build one. And that means you have to get plastic sheet and enclose the truck, or the part you are painting, dehumidify the enclosure and then paint it with the can.
If it does it again then as you are saying, replace the clear paint. Weren't you going to do that anyway? Do that, then enclose the truck and then try it in the enclosure. If you have a heater, try that to reduce the humidity, and there may be other ways and you may need to look that up, I don't know. To be honest I don't know how paint booths are dehumidified. It easy to control the temp by air conditioning the room, and maybe that's how it's done by the A/C being low in humidity as it's blown into the room.
Good luck and I hope your hood turns out okay.