I'd think any back-pressure in the burner section would trigger safety shut down or raise temperatures until it damaged/sagged/ some vital component or fusible link and shut it down for good.
Maybe loosely coupling it to a ramped upward flue that was split lengthwise into top/bottom clamshells that has level hardware cloth 'shelves' propped onto riveted brackets - make it so when the first batch of chips has it's fireball minute that feeds the next level which feeds the next level, etc., and once the all have 'fired' to the point of no/low volatiles those shelves easily tonged out of the flue chamber to dump chips in a collection bin.
EDIT: By loosely coupled I mean only part of the output gets forced into the burn chamber flue, if the flue is wide open say maybe 70% gets ducted and if the flue is crammed full of chips and low air flow then maybe 20% of heater output gets shunted into the chamber.
Just talking out loud there...