The build has officially begun.  This week, I ordered 2000lb HD axle-less suspension from Timbren.  It's probably overkill, but I wanted to ensure I have ground clearance so that going over water gaps and minor stuff isn't dragging bottom going into BLM sites.  And my next tow vehicle will probably have a bit more ground clearance.
Once everything is in town, I'll order steel and start cutting/drilling all the holes necessary to install lights, the axles, receiver, fender braces and so on.