Looking at that, is it worth looking round somewhere like B&Q to see if there is a cupboard latch that would do the trick, screwed to the finisher plastic piece? Like the ones with a flared piece and a double sprung ball joint, but in plastic? Probably get a packful for pennies of something that will engineer to fit that way. Possibly just need to be pinned or screwed into the plastic section on the finisher?
Or get a few tiny neodydium magnets to glue into the finisher plastic piece and insert a pice of steel wire in the tit on the body clip. They should pull strong enough to hold tight.