I don’t know why GCWR rating would come into play (it’s more about the hitch weight - the actual download on the hitchbar) as the weight of rack and bikes is minimal, and at least on our coach the toad rating is 10k., not 5, and hitch wt. 500 - 1000 lbs.? as I recall.
With the right rack you can mount on either coach or toad, which is handy when the coach isn’t involved in an outing. Consider either a “pass-thru” rack with male and female hitch configurations, or the extended hitch bar/clamp-on type. My Weyerhaeuser machinist brotherinlaw built us the former style (insert/receiver/extension adapter with a “T’d” upright bar welded to it) in a basic but stout form 30 years ago for our Pace Arrow. Kinda wish we still had it.
We later got one where the bike-holding arms folded down so on our canopied mini pickup or Explorer toad the tailgate could be lifted up without removing bikes and rack. But it isn’t pass-through and only goes on the toad when towing, or coach when not. On the coach it’s nice because the bikes can fold down so they aren’t in the way of the engine door.
One issue that arose with that one is if a bike cover is contemplated for long dusty or wet trips, you are out of luck trying to tow because the cover will block the toad’s taillights. Bike covers are only good for large coaches, not narrower vehicles.
I can’t advise as to today’s available racks as it’s been years since we shopped for one, given their expense. But the ones the guys linked to above certainly sound at least functionally palatable. I can attest that Yakima has been at it as long as any outfit, and would be a brand worth serious consideration.
Joel
Addendum: after a little searching, pass-through models seem few and far between anymore. Those that engender possibilities aren’t practical because their extension is only rated to 2000 lbs., encompassing only light trailers rather than toads. A clamp-on/slip-on style seems the only realistic option, aside from welding up your own on a stout insert.