I've been thinking about this because we have two small children, and although I try to teach them a lot of good things they should and shouldn't do, I realize they may occasionally do something different.
Anyway, the thought I had was to attach metal rings (not sure the name for this piece of harware, but basically a rectangular piece of metal with four screw holes and a half ring coming off the top) where each of the straps hangs down. Then rip off the stupid plastic latches, and instead run a padlock through the strap and the metal ring. The big disadvantage would be the inconvenience of taking off four locks each time you used it, but it seems to me if you had a cover lifter, there might be enough play in the straps on that side that you wouldn't have to undo those.