I have hard cap on the bed of my 2010 Pro 4X. I was thinking about carrying extra gas in a new steel jerry can. Would it be safe to do so? I wouldn't want a build up vapor creating an unwanted fire ball.
I have a cap that occasionally goes on my truck and I don't think I would ever put a gas can of any sorts in the back. Supposed to be in an open area. A tray for the back of the truck like a receiver tray would be a good place for em' too plus allow you to carry more stuff. Just sayin', do your thing though.
I would not, and I take plenty of crazy chances. That cover will act as a fume retainer just waiting for you to open and have any spark near by. Remember the fumes are way worse then the fuel itself.