I've cooked 30-40 bbs on similar set-ups many times. I always do the bulk of the cooking indirect (just like when I cook on a WSM) and I cook high heat (like the WSM as well), with temps of ~325 for most of the cook, higher after foiling.
(You don't have to foil. I've done many cooks without. But it does give you an op to add flavor and even out the cooking - and it gives you a bit of a break once they're back in the cooker foiled. It ain't daunting at all; I can foil 40 racks in less than 10 minutes - no reason you can't do the same.)
I cook indirect, periodically rotating ribs from hotter spots to cooler spots, periodically flipping, if needed, etc., so all cook as evenly and within as close to the same time period as the others. How often I have to move them depends on quantity, grate size, where the fuel is located. I am not beyond stacking racks on top of each other to save space, as needed, though one must rearrange the stacks periodically for even cooking.
I cook till deeply colored (the same as I do on my WSM) then foil, if foiling. (If I'm not foiling I just keep at it till tenderness is achieved.) For foiling, I prefer one rack per foil piece, along with a few tablespoons of whatever I'm using for foiling liquid, meat side down, and will return them to the cooker and stack them as needed for space considerations, rotating the stacks in their entirety, as well as the individual racks within the stacks, periodically. (I tend to do things in 5-7 minute intervals. There is no way to keep track of everything I've done so I don't - and I don't worry about it.)
Just like on the WSM, I cook till tender while in the foil. I never sauce ribs for serving (can't stand that) but sometimes thinly glaze - and that is something I do for large rib cooks as it evens out flavor disparities caused by all the handling during cooking. As the ribs are done I remove them to a side table, draining foil juices to finish the sauce with, and flip them meat side up. I paint on a thin veneer of glaze and they sit till all are out of the cooker. If not serving soon I drape lightly with plastic to keep off critters. For serving, I return to the cooker, several slabs at a time, paint with glaze, allow to heat several minutes, then stack off to a cooler side, adding new slabs to the cooker. The finished stack gets sliced and panned for serving while the next group is finishing.
Hope this helps.