Hi Glen and welcome to casting.
I use an outdoor burner for smelting also. I think it was an OLD plumbers unit. Looks a lot like the modern turkey boiler.
I use an old dutch oven. When it gets too low to dip I grab the side handles with vise grips or channel locks to get the last out.
Be interested on how the bottom of a propane tank works for you.
Most of the time I am now using wood chips for fluxing. Chain saw chips from cutting fire wood so there is a bit of chain lube.
The LEE lead hardness tester is fairly cheap and works well. Read the tests of various hardness testers on LASC site. While you are there download the free book " From Ingot to Target": A Cast Bullet Guide for Handgunners - A joint effort by Glen E. Fryxell and Robert L. Applegate. It is the best book out there. Lots of other gems there also.
I haven't found any lube better than Fryxell's take on Alox: Moly lube (Wally World or any AP store) and bees wax.