Yakima makes a side mount gutter racks and mounts. Mounting to the side is strong and easy. I use threaded galvanized pipe with endcaps. You can also hide a shower enclosure rod in them
Bike4mee, thanks for the side mount idea, had those brackets on a 87 suburban, worked great. Side mounting would also save me from relocating the solar panel for the roof tracks. Not drilling several holes in the roof is another plus.