Funny, just came across this thread after going through this two days ago - getting a Latex 365 off a truck with only a typical lift gate. Packaged was about 120" long 740lbs and HP's palatalization wouldn't win any awards. Renting a forklift for 30min would have been the call (the flatbed idea sounds great also), but there we were, sitting in our alley, in the rain, with the truck driver staring at me and no time to go rent a forklift. Lumber yard down the street wouldn't allow theirs off premises.
First thought was find another delivery truck in the neighborhood, have them backup to ours and use two lift gates to lower the printer to the ground. None around. Next option was pull the printer onto the lift diagonally let it overhang off the corner, trying to keep it within HP's spec for support (better pallets would have helped...) and letting our pallet jack float in space for a bit. Then there was enough room to slide the tail end out of the truck so it sat horizontally across the lift, then and lower the printer to the ground. After that pick it with a pallet jack on each end and take it where you want.
For smaller rotating and sliding movements good ole' Archimedes comes in very handy (give me a lever and I can move the world). We keep a hefty "spud bar" around the shop that can be used to (slowly) but easily inch pallets and equipment around in a pinch. Stick the flat end of the bar about 2-3" under a pallet, lift the other end to pry/slide, repeat and you can make surprising progress that is gentle on the equipment. Overall it actually worked really smoothly, but I'll make better plans for the next one.
Few pix -
https://drive.google.com/drive/folders/1-8jkZIOwkef3WLYyJ-cT8nsBO_N932bM?usp=sharing