Different max stack sizes for different GUI slots

Using MCreator 2025.2 

I have a GUI with 6 slots attached to a block entity. In the block entity settings I have max stack size set to 1, but the 6th slot needs to be able to hold a full stack. Unfortunately I haven't had much luck doing this via procedure and there doesn't seem to be a per-slot max stack size setting anywhere in the GUI nor the block settings. Does anyone have a good work-around?

When max stack size is set to 1, all slots work as intended and only hold one item at a time, shift clicking only puts one item in each slot, etc., but the last slot is to hold coal and other fuels so it needs to be able to stack ideally.