Hi there Robert!
Your idea has been used in many charcoal kilns. Garry Gillmore has a set of videos on youtube, showing a simple kiln made this way, and many others.
Althugh, like Garry does, is better (cheaper, easyer) to use wood as priming heat sorce, as the charcoal made from it is not wasted if done propperly.
Dry wood is essential!
Allso, in my experiance, althugh generaly such indirectly heated systems require some practice to operate and are more complex, in terms of bbq charcoal making, they are better.
A TLUD makes high qualyty engine grade charcoal FAST, but it tends to produce small bits of char.
If one wants biger chunks, slower cooking is esential. Fast gas escape from the center of a wood peace produces cracks that brake apart your char chunks. Great for a gasifier, not so much for a bbq.
The premium Japanese white charcoal is cooked slowly over a period of 3 days, the resault is charcoal with the original shape of wood. Rock hard, and it glows long and strong.