Ribs look great Fred.
Have you thought of buying or making a rib rack? I've noticed no real difference in taste smoking them flat or on edge, if anything, I'd say they come out better using the rack. (Less direct heat more smoke) Would make it more difficult if you wanted to sauce them, however.
I bet with a well designed rack you could fit another 3-4 (or more) slabs in there.
My offset is not long, but wider than most. I can get 4 slabs of baby backs in there laying them flat. Being a "reverse" there is an opening at the far end, which I usually avoid putting meat directly over. So perhaps I could fit another rack in that spot, just haven't tried.
The rack I made actually will hold 11 slabs of ribs. I sacrificed the center slot to put in a handle, so dropped that to 10. However, I usually only cook 6, as I like having a large empty space between each rack for maximum smoke flow. During my last cook I did some measurements and figured I could build one to hold 9 racks of ribs, with adequate space between each rack, if I used flat metal instead of the threaded rod I used, and built the handle differently. That design would require it to be welded, and not having a welder at my disposal negates me building it.
Not a big thing, as 6 slabs of ribs is still a lot for the three of us, and going out to cook more is something I always enjoy doing anyway.