I have a 87 Li'l Bigfoot
. I removed the black vinyl (?) strip and removed all the rusting screws around the belly band. I replaced the old screws with slightly beefier ones. I noticed they sucked in the sides to provide a better seal. I used ProFlexRV sealant in the screw holes and over the new screw heads.
I know a complete belly band overhaul would have been better but more work and time. My fix has kept the water out for 3 years now, hoping for several more.
Added comment: I removed all the old silicone around the band. Lots of work but worth it. I replaced with a small film of ProFlexRV sealant (color matched). I did this to the entire band, to save me doing patches later.