[acidrain]

You'll have to hang the parts... if they touch the sides or each other, there will be a dark place there.

Don't use aluminum pots for sealer... they will make the sealer chalky and generally unusable.

I use a propane stove and a canning pot, but I'm building a larger tank heated with a 2500w/240vac hot water tank heater.

I think the way you are doing it is fine... just hang the parts with a bit of space between them.
I also use foam for a lot of things including lids. If you build a box sized to hold your bin plus 2 inches of foam as surrounding insulation, it will help support the bin and you'll be surprised how long the sealer will hold the heat. Finish it off with a tight fitting foam lid (that fits inside the vessel), and it will keep condensation contained, and crud out of your sealer.