@tony b, @Aussie Ora, I hid that post so the world doesn't know your address.
"So now the question is - how did BBQ sauce & rubs suddenly become "Hazmat??" Everything is clearly described on the shipping label and customs forms. "
My guess is the sauce being a liquid. When you click through the keypad at the post office one of the things you agree to /certify is that the package doesn't contain any liquids. Somebody down the line was having a bad day and felt like being a jerk.
I've put vinegar on the declaration form in the past and worried about it so I started putting condiments. I figure condiments is about as vague as I could get.
The legs will also let you set the entire unit on a flat surface with the extension sticking out the bottom. No backdraft is necessary.. Think of it as distructive distillation of the wood.
The vapor/gas comes out of the wood and builds pressure. My huge charcoal kiln had a 4" pipe and shot a 4' flame for hours while carbonizing a load.
I've seen the use of the bolt through the lid before. If you're willing to put that much work into it, especially cutting the handle off the lid to make room for the bolt and wing nut. Unless the legs have something sturdy to sit on and not just stick into the charcoal bed, what's to be gained? Will there be enough backdraft flow from your extended tube back into the pot to keep the wood smoldering? Worth a shot as an experiment. Let us know how it works out.