Full disclosure I don't own a Gladiator (yet) or the factory bed cover.
The problem with the factory cover is it doesn't accommodate bed racks. I personally want to carry skis and bikes (at least) but still have a covered bed. The factory cover is not a great solution for that.
I am old school with this stuff, too, but the safety features are worth it. You'll get an insurance discount and they may actually prevent you from being hurt someday.
True story: My wife was driving along on a random Saturday afternoon about 6 weeks ago with my 6 year old son in the back seat...
So the JCR rack will work with certain "inside the rails" tonneau covers. It looks like the American Adventure Labs rack would be compatible with covers in the same way.
Does anyone else have any insight into this?
Sorry for your trouble but what do you expect? You want to do this whole thing from behind a keyboard. I don't blame you but think about it from their perspective. People flake out on "deals" all the time. I don't blame them for not holding the truck without some cold hard cash and a signature...