You are correct, most of the loaders I saw were for single hives. I was hoping to find a design in which the boom was sturdy enough to support the weight of 4 colonies (which I know must be a fairly sturdy boom, given the weight of even a single colony). If such a boom can be built affordably, I would load and unload the pallets with the boom by placing them as far from the trailer as the boom would reach. I may have to move the trailer a few times in order to place the pallets where I want them, or to pick them up for loading.