I have not tried it, but was thinking this morning that a tamale cooker might make a good basket. A few holes around the side near the bottom would pass air into the basket. Tamale cookers have a steamer built in. The holes in the steamer tray (which is about 3" from the bottom) would be enough for the fire, but I would probably want to enlarge them to drop ash better into the bottom of the cooker.
It would be an experiment to see if the cooker could radiate heat quickly enough to prevent softening - but as people are already using them for Smokie Joe mini-uds pits, I bet it would work. It would be a self contained ash pan/fire box unit - and probably not all that more expensive than expanded metal would cost.
That said, since I am already planning on making a mini-uds, might try to make something that works for both.