What about just doing away with the ash catcher bowl and putting down a tray on the ground and sit the legs for the fire pan on that?
OR.....just install bolts in the ash pan, leaving them long so that they create the spacer. That would be cheapest option I think. You know, just put the bolt head inside the charcoal pan with the bolt sticking out on the outside, then put a nut on. The "tip" of the bolt then rests on the ash pan. You could put that anywhere and make it as long or short as you needed.
18.5", 22.5" OTS
Large BGE (chambersuac's)
The Fiery Furnace (chambersuac's)
Big JT's Smokin' BBQ Competition Team