Looks like you did an awesome job with the racks... more peace of mind than either hitch or inside tt. I'm sure there are folks who would be interested in blueprints... although your pictures make it look "fairly" simple.
Just curious, if you have 5.5' truck bed -or- larger size? Mine is the short bed and it's a couple inches short; but when I turn bikes slightly to the side, they fit OK. As of now I just bungee them to the side. I'm thinking maybe your rack could work... do you think they would be stable if I cut them down to hold 2 bikes instead of 4?
2012 Ford F150 4x4, 5.0L, 3.55
2011 Rockwood MiniLite 1809s
E2 WDH 600/6000lbs