If it will fit the RTV 500,Go with a overhead gun rack. They are great....
We have them installed on the RTV 900's and wouldn't have anything else.
Also, have a place to slide a third rifle in. The third rifle is there for shooting wild boars >>>> It hangs above & behind your head of the RTV >>>>
Would give you the names of these racks / gun storage. But learned, website frowns on naming things on the site ....
Picture is kinda leaning, best I could do for now !!!! Click on picture to enlarge ....
..... two guns