Thanks for the quick reply! That's how I've tried to do it, I have a triggerbox1 pinned to the lift platform to count the objects overlapping it (to add as weight) and triggerbox2 to the side to prevent the objects interlapping only barely with the lift and still counting towards the weight.
This is working so far as it should, counter adds the weight when objects overlap with triggerbox1 only and substracts weight when not, but problems arise if there's an object next to the lift and other objects are stacked over it, as demonstrated by this mockup picture:
As the upper objects are overlapping with triggerbox1 only, they still add to the weight counter, even when in reality their weight is not on the lift platform at all. I probably need an instance value for boxes to state whether they're standing on the lift or not or something. Not sure yet how to approach it, but if any suggestions come to mind as to how to fix this I would be very happy to hear about them:)