Had this same issue earlier this year on our 2011 28BHS, except I just happened to look down and spot the straps hanging down after they had broken loose. Holy cow! The tanks were full and we were ready to hit the road and the tank in question was in front of the axle. Thank God it didn't drop!! I inspected the rest of the screws and straps and saw the same stuff in the pictures of the OP. The self tapping screws had completely rusted through and the heads had broken off. Our Jayco dealer was great and drove up from Davenport (80 miles away) to replace all the screws on the tank straps with new ones. They looked somewhat bigger, but I got underneath and sprayed rust inhibiting paint on them as well. So far, so good. No more problems! This was a serious safety issue and I thought seriously about what would have happened at 55-60 mph. Check those straps!
2012 JayFlight 32TSBH (Elite, Thermal, Tech Packages, Power Awning)
2009 Ford F-150 SuperCrew Platinum 5.4L V8/3.73 Limited Slip, 6.5' Bed, Max Tow, and Integrated Brake Controller