I haven't done this myself yet but I have discussed it with four or five who have been canning this way. It's really a matter of whether the grill/fish cooker/whatever can put out sufficient heat fast enough and whether it's controllable enough. I think most campstoves would have a problem putting out heat fast enough but some grills ought to be able to handle it and most of the fish cookers/turkey fryers certainly can.(posted 9668 days ago)The only way to know for sure is to experiment with a canner load, maybe just jars of water, and see if you can make it work. I'm going to use a fish cooker myself and put it on the porch. This way I can keep the heat outside and do the pre-processing inside without running the a/c full blast. I might have to change the regulator to get the amount of control I want or perhaps might just put a thick metal plate on top of the burner to moderate the heat.
........Alan.
The Prudent Food Storage FAQ, v3.5