Both drawers in my build are essentially on runners. The left drawer has a narrow ledge in both bottom corners of the box. The fully loaded drawer slides on those and rides over the pull-out shelf / tray. In the top corners of that box there are similar rails that fit very close to the top edges of the sides of the drawer. That close fit allows me to pull the drawer very far out and still have it cantilevered without any droop. And the top rails also allow me to have a full-span top hatch in the platform so I can still access recovery and other emergency gear if I'm unable ot open the rear hatch or drawer. That hatch design required the addition of the upper guide rails to span that hatch opening and keep the drawer from tipping as the rear of the drawer enters the hatch area.
The right drawer, only partially filled - contents vary depending on what I'm up to - glides on two 1" wide strips of pressboard. So the full bottom of the drawers doesn't touch anything, greatly reducing the overall drag. It's sides are full height IIRC, the platform deck is what keeps the drawer from tipping.
I used sturdy steel paddle latches and the way they open makes it a natural action to just keep lifting as I pull on the drawers. I'm a big mesomorph and fat, I have no problem convincing my platform drawers to do what I want. Someone sleight or prone to wearing skinny jeans and texting all day might have a bit of a struggle. On the flip side, on uneven ground, the drawers stop wherever I let them go. They don't drift all the way open or closed due to ground slope, as drawers with metal bearing-slides are wont to do.
I have not yet felt the need to add any glide material, nylon or teflon tape, graphite dry lube or anything else. At some point next year I might do a follow-up and pull the drawers and show any wear and tear. I am using / opening them often, as well as loading all sorts of heavy gear and equipment on top of them. My sacrificial edge mouldings are certainly getting sacrificed. Maybe I'll do the exam next Spring. I'm expecting to finish my solar integration and any other power port mods and will be looking to re-face the whole platform build with some highly-figured exotic hardwood.
eta the right hand drawer, note the height and fitment of the drawer sides
This is looking into the left hand box. My choice of flush / hidden cabinet door hinges required me to lower the sides of the drawer, which in turn led to the use of a top rail to trap the drawer vertically. You can also see the bottom rails. The slide out tray fits between them. Too, you can see those rails are plywood and oriented vertically. About the worst for drag, yet still working. I might re-work them with solid pine and have a smoother face against the drawer bottom, for an easier glide.
The extension of those top rails into the hatch area is what holds down the end of the drawer and allows them to open so far with very little deflection. The drawer works just the same in the vehicle, fully loaded with tools and gear.
That same sort of close vertical fit is what lets me extend the tray quite far. It's only 3/4" thick material, so there is some deflection if you put a lot of weight on it while extended fully.
