I wasn't happy with the mortises on the legs so I filled them with some scrap pieces cut to size (with matched grain direction), moved them in another ~1/16" and went over to a local guild members house to recut them on his hollow chisel mortiser. After those were done, I cut a 3/8" grove in the legs and rails and cut a rabbet on the back of some 1/2" sapele ply for the panels to ride in the groove. I blew out the back of one of the legs when I got a catch in the router bit as I cut the groove but it won't affect it in any visible or structural way so I am just leaving it.
Next step is to mortise the lower 4 rails in to support the base of the cage and to support the shelf.
I would get them at Lee Valley, but for the four clamps I was thinking of getting (2x40" and 2x31") it'll cost me an extra $50 compared to buying the K body clamps at Busy Bee. It seems like the Lee Valley ones are about $10-$12 more per clamp in pretty much all sizes. There aren't really many other local options here, at least not stores that have sales on anything. I actually like the staff at our local Busy Bee, but they're very large power tool focused so I tend not to be in there a lot.