Hi all,
Good sources for such things are the manufacturers who make roll out trays for large motor homes with "basement" storage bays. Some go the full width of the coach (nearly 8') and are designed to carry a lot of weight. They come in different widths and have locks to keep them in place while driving. They should fit the length of a van and simple racks/bins can be built on top to fit the width and contours required to clear the wheel wells yet the whole thing could slide out as far as you need to access everything. One significant advantage to this slide out unit is it can be designed to allow access from the outside (the part of the rack that is against the walls of the van when inside) as well or instead of access through a center isle that consumes so much of the net space available inside a van.
Nope, I don't have or need one, but I have owned and used these slide out trays on motor coaches with great success. When we lived full time in one of these "rolling condos" for four years while looking for an interesting building to restore into our studio, gallery and living quarters, we carried everything we needed for four season living on such trays. Roll them out to access everything from end to end.
Jerry
