Hey, I have the MBXL, too! I woke up this morning and the first thought was this post! And the solution. Taking everything into you said into consideration, what wasn't clear to me last night now is; I initially couldn't get past charcoal flavor as opposed to what I think is your desire of the flavoring the charcoal produces. I went to my first comp BBQ competition yesterday to try what is considered competition worthy and was STUNNED to get a teaser rack of ribs that not only had been laid on a pit/rack that had obviously been used last Sunday at the church fish fry (I know this taste because my poor husband went to try to use the MBXL smoker I'd bought HIM for Christmas a couple of days after smoking a side of salmon; he said, and I agree, it was the best salmon pork he'd ever had--he hasn't touched it since, and now I designate racks), but the pieces that didn't smell like fish tasted like charcoal... Fresh charcoal...
Sooo, I finally got the got my head wrapped around what you're looking for (not the fresh charcoal flavor) -- and how to do it...
Start your charcoal off in your grill, til it has burned off to the point that you'd start grilling... Assuming that you've already gotten your smoker up to temp and meat is already on, and your woods smoking nicely--whip out your pan, using a spatula, tongs, or whatever, scoop out your charcoal and add to your pan and whip that bad boy back into your smoker! Boom, done! Watch you temps over the next few minutes to see if the charcoal is going to bump your heat up, and be prepared to drop your propane down as low as it will go or even turn it off for a bit to level your temps!