I tried some of this on a crappy 12' heavily abused rowboat.
After 4 rivets were replaced, I scraped off the JB-Weld that was covering some actual holes in the sheet metal itself.
The holes were likely from bird crap and salt air.
Holes were small, less than 2 mm.
I used MAP gas as suggested. The stuff works, but to leave a clean flat professional surface, it would take some practice.
The thing that was most concerning was the bowing outward of the sheet metal as it heated. It rose quite a bit, almost an inch I would guess. But at that point it was at the melting point of the HTS-2000. It did go back when it cooled. I followed the instructions exactly. It flowed pretty nicely. The finished product was a little higher than the bottom of course but nothing drastic. I sanded a little after just for knowledge, and the HTS-2000 is much harder than the aluminum.