Our 1991 Bigfoot
17 came with a fiberglass propane
bottle/battery cover. The cover, really a pain to remove and install, had no access to propane
bottle valves. On eBay we found some 6" round deck plates. These Rabud brand covers twist lock in 1/4 turn, rather than screw in after several turns or pop out like other deck plates. This is most convenient. The eBay seller listed them as off-white. When they arrived we were delighted to discover they were actually almond, a perfect match for the trailer. When checking the manufacturer's website I did not see that color listed so perhaps it has been discontinued.
Installation was not difficult. After marking the 6 1/2" cutout circles on the cover, a friend with a steadier hand cut the holes with a jigsaw. I cleaned up the holes with a rattail file so that the plate flanges sat on the cover without any pushing required. I drilled pilot holes for the stainless steel screws I used, ran a bead of silicone on the underside of the flange, then screwed the flanges to the cover.