Here's some pics of the unistrut and how I have it set up in my cargo trailer:
Unistrut brochure shows basics of nut/bolt/bracket and channels:
my unistrut is only half as deep as "normal"
The bracket I made is an eye bolt cut short, placed thru a small section of angle iron and welded to a unistrut nut (see first pic). The angle iron is then bolted to the 3/4" plywood so that the edge of the plywood rests along the entire length of the top of the unistrut.
To install/remove, simple give the eyebolt 1/4 turn and the leading edge of the shelves are supported by running the chain back to the next set of eyebolts (top is attached to holes drilled in bows).
The pics exp. it a lot better than I can
Weight is approx 1lb/ft and it will support around 600lbs on an 18" span (incredibly strong stuff). The entire line of unistrut looks just like an erector set for big kids
Hope it helps.