Could just add a
melee-centric PFC kit with a heavy machete or something that tears down resin structures with ease. I think the kit system has proven that people love using PFC as a 'modular role' and there ARE players who enjoy tearing down resin structures, it's just that machetes (the best standard marine cutting-tool available) are basically crap against Hivelord resin.
edit: Also, how about a "Dog-Tag Locator" mode on the motion detector? Seems like a basic, easy solution to all but the most elaborate body-hiding. There could even be a different colored 'blip' if the body still has 'vital signs' (i.e. defibable).
These two additions, even in their most bare-bones forms, would be a powerful, non-rule based solution that adds gameplay to the marine side and doesn't force xenos to question how they build their hive when unmovable corpses are around.