twodogsdaddy
Dreamer has my vote. Perhaps half van operators place E-track on the floor as pictured above. That configuration is not my personal preference because of the dirt/litter that gathers in the slots and, I think, the eventual liklihood that an errant pallet nail or a protrusion, such as a metal tub leg, could fetch up in the slots and make the movement of a skid up forward in the box difficult.
I've found success with E-track mounted on a self constructed wall, in my vans, at floor level and at 16" or 24" above the floor. I use 2X4's in E-track sockets as seen in the foto above. the floor level bar secures pallets and the upper bar secures the freight. Even works well with 55 gal drums.
Additionally, I never use chains, ropes or straps to pull any weight of skid aft to the rear doors. I use a water base polyurethane coating on a sheet of Baltic Birch plywood for the floor. I then spray silicone lube on thick fuzzy doormats (cut in Half). I place four pieces of these lubed mats under each pallet so they can be muscled around the cargo area. Rene' has pushed 1500# skids around, much to the amazement of towmotor operators. This method requires good securement of all freight, but this is a good thing.