Very similar to what I did. Great job! I like having the bikes behind the cab where I can see them. Plus they don't move at all up there. This is how I did mine.
I love not having to worry about them. Plus it is easy to load, just put bikes in bed and back up near hitch and load 'em.
2012 Sandpiper 365SAQ weighing @ 15k, Onan, 2nd air, slide toppers, TST
2013 F350 6.7L Lariat 4x4 CC DRW,Viair 1007, Ride-Rites, Edge CTS, B&W
2001 Chevy 3500CC DRW 4x4, 8.1L, 4.10 gears w/ Detroit TrueTrac
2001 Ford Excursion Limited 4x4 7.3L,V/B Spring Mod, ProComps, Hellwig Swaybar, & other 'Necessities'