You would need to set that heater pretty high ......up to wax melting temp would you not? That does not overheat the honey?I knocked a hole for a 3/4 inch Meyers hub in the bottom of a 55 gal barrel with a valve to drain and put all my cappings in there and use a drum heater to melt the wax and drain the honey off before it over heats.
Should the capping tank be made of a food safe plastic or that really doesn't matter since it is not used as a storage tank?I use a plastic storage box that I bought at WALLY WORLD. I made a 1" square piece of wood long enough to go across the narrow part, (you will have to use some sort of an anchor bolt (one on each end) to hold this in place) with a nail long enough to stick up through the wood to put the frame on so it would swivel around. I leave the cap-pings in the box with a drain hole into a gallon jar with a Knee High stocking stretched over the mouth to strain the honey. I use one box for cappings and one for the uncapped frames. Works GREAT for me.
You could buy a Maxant Bottling tank and uncap into that. When it gets full warm things up, drain of the honey, and then turn up the heat and melt the cappings.I guess that all depends on the end use of your product.
Ideally food grade would be the best method, unless doing something in a pinch!