Rib hooks work well, or an upright rib rack. I find I can get 3-4 full slabs of BB ribs into the Model #1 by cutting them in half, placing two halves (one full slab) onto the bottom smoker rack in the lowest position, then using an upright rib rack on the upper smoker rack (in the middle position).
I use the Brinkman Pro Q rib rack. Fits perfectly in the Model #1, and can hold many slabs o' ribs.
http://www.ebay.com/itm/BBQ-Rib-Rack-ProQ-Pro-Q-New-/120788320195#vi-content