I recently purchased a 2013 Layton walkabout. I trying to install roof vent covers. But there are 4 eyelets that are built into the roof around the vent. They are right were the brackets would go for ...
At one time there was a vent cover over it. They eyelets had a pin in them for easy removal. The cover was probably damaged and removed and never replaced. I have something (similar) over all my vent covers on mine. All of then are easily removed by pulling a cotter pin and slipping out a catch pin. Looks similar, but different too than yours.