Thanks for the suggestions. I wound up using the lava rock pan suggestion and the top of the ECB fits more or less snugly on top of the lava pan.
My next issue is that I've bit the bullet on the charcoal ring and decided it'd be a good thing to do. I also decided to emulate this guy's build, as I'm certainly no welder:
So off to HD I went. I picked up the 24" x 24" sheet of expanded metal, as folks have suggested to get. To cut said metal, I also picked up a laser guided jig saw with a set of blades, along with some of the SS hardware for the build, with the intention of now having this sit on top of the 10.5" WSJG charcoal grate.
For those that fabricated a round charcoal ring for a modded out ECB, how tall did you make it? It would 10.5" in diameter to match the WSJG charcoal grill, but it looks like, judging from the position of the water bowl, that 6'" might be about right, but I also like the extra capacity if it were to ever come in handy so maybe 8"?
The charcoal ring was going to sit in the charcoal pan (raised with bolts) that I had drilled holes in, yet now it seems like, if I pop some SS bolts onto the grate and put the grate in the lava pan, I might not even need to bother with the ECB charcoal pan because the raised grate should provide airflow and sufficient space for ash removal. Go figure. Looks like I've gone overboard on the mods a bit. I'll have to take pics when it's all said and done.