The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
I see you are new here so 1st, welcome to the forum.
How old is the Mallard?
Is the belly enclosed with a fabric material?
If the belly is enclosed, I'm wondering if maybe you have a leak somewhere and the straps are staying wet and rusting away. If the belly is enclosed, the straps should not see any moisture IMHO.
There was a recent report here about a brand new camper that lost the fresh water tank leaving the dealer. There was some water in it, and the factory never strapped it in!!