This is an awesome thread - thank you.
We, too, have no factory rails (she said, with despair). My husband is hell-bent on ripping our current solar set-up off the roof and re-doing it with 8020. Our Interstate is first-gen, so we have the stainless steel “roof rack” that Airstream kludged on there mostly for style, although they did declare in the owner’s manual that it is capable of supporting up to 100 pounds. That thing has been a hot mess since Day One of this van’s life - I am constantly struggling with footer leaks because it wasn’t installed properly. My husband wants it gone but I keep asking him, “With that roof configuration, how exactly do you propose to install an alternative that is not an even bigger mess?!”