I looked at that and similar solutions and ended up going with tracks on the roof along with crossbars. I was concerned about the integrity of the raingutter mount with relatively large load up there, although I don't have any specific data to say it's a problem. A bit more to the installation than what you're considering. I've got a cargo basket and cargo box that I can put up there, and I've hauled up to 3 sit on top kayaks. I also reinforced the track mount points with an aluminum backer plate so the load is well distributed. This seemed to leave the hard top to tub connections as the potential weak point, so I upgraded those too. Here's a write-up if you're interested in this alternative.