On really coarse hair the foil shaver always leaves this ghost line for me too. Tried your corner trick and it works way better than I expected. I also started stretching the skin a little tighter while doing that corner pass and it helped even more.

Total bummer" is right, but I think the REAL pain is when it's a specialty tool you only use once a year and you can't even remember where you bought it. Like that time my weird jigsaw blade adapter just snapped in the middle of cutting a circle for a vanity project. I spent more time hunting for a replacement online than I did on the actual cut. Meanwhile the project sat there mocking me for a week. Makes you wonder if some tools are DESIGNED to fail at the worst possible moment.

Did the guy really fix it or just hide the problem? A block and a mallet on a modern truck frame sounds like a temporary bandaid. That F150 has aluminum panels now, not like the old steel ones you could bang back into shape. Dave might have just worked the gap for the moment but the actual alignment issue is probably deeper in the mounting points. The customer watching probably had a point if they've dealt with frame damage before cause that kind of quick fix can mess up door sealing or even safety in a crash. I'd rather see someone take their time with real tools than pretend a 10 minute whack job is actual repair work.

My neighbor tried that trick once and said it worked great on his old house.

Are you sure you just didn't pack the right gear for an 18-mile hike in the mountains, even in July? Did you actually check recent trail conditions before you went, or just assume it would be dry?