Hi Matthew. Kind of two answers for me...
1. My skyboards vary a bit in height, but are generally around 7" above the plywood top. All my modules, except outside corners, have skyboards.
1. a. My modules vary in depth as well, from the original 8.5" or so to 12". Anything deeper than 12" can cause problems with the bus wires and wiring connections.
2. Most of my modules are transported with wood bolted to the ends. The modules are nested but I don't depend on the skyboards to hold them. Some modules are transported in shelf units, where they slide in and are held in place with bungee cords. These are quicker to unload but take up more space.
Hope this helps. Geoff