That helps. It’s morning and I’m on the first coffee and I forgot it was a truck topper… not an actual pop up camper. My bad… hold my coffee, let me grab my brain!!
Let me say, IMHO, the 8kw diesel heater will blast you out of that topper! I did a heater test and within an hour of runtime on max, the internal temps of my truck topper was well over 130*. If you strap the heater on a tire step, plumb the hose thru a quick disconnect adapter thru the door or side, you will be set! The advertised gph states that if you run constantly, the supplied tank will run 8-12 hours. As we know, that depends!!
Here’s the catch. Your F150 is regular gas, these heaters would require carrying a yellow diesel fuel can if you go out for a weekend. Another consideration I guess.
The water heater. For me, I made a bracket on the drivers side of my topper and I just hang the propane heater while in use. Easy access to my propane lines, kitchen sink and the water lines can be extended to reach the shower tent