1/16 wall thickness is really pushing it if you are going gas. 1/8" tube is enough, but I would be afraid of the heat from the burner. I made my rig out of 1/8 x 1 1/2" andgle and it is more than enough. and i do up to 25 gal batches. If it were me, I would go with 10ga square tube by 1". It will be more than strong enough, and still reasonable in price. Doesn't have to be over kill.
Are You Going to Drink all That?