Adventure Trailers implanted captured nuts (I don't know the formal name for them)...
Rivnuts or Plusnuts. It is well worth the investment to get a good hand-tool installation part if you're going to be doing a lot of mods. However I bolted my DIY drawer platform directly to the existing 3rd row seat captive nuts and existing fasteners. Save the money on the prefab drawers and build your own. It's insane what an off-the-shelf drawer system costs vs what you can do yourself.
I spent a total of maybe $250 on materials and a day or so of labor on what suits us just fine. Not as pretty as an AT or AO drawer "sy$tem" but really, $250 vs as much as $2500? Wasn't in the cards and those savings get spent pretty quickly elsewhere on the truck where you can't DIY: bumpers, lights etc.
Yes pretty ghetto by comparison, but it has served us well for 3+ years. It's basically some craigslist aluminum restaurant shelving bolted together with salvage network rack parts, aluminum stock, plywood and outdoor carpeting from Costco. Did without the slides and building drawers, and just got some plastic ones under-bed ones from The Container store.