The ratchet straps are not really recommended for lifting, and you would also want check the load capacity of the beams. An easy and fairly safe way would be similar to how we have taken our boat off its trailer (and it weighs in at 3000 to 3500kg). If you have the back of the camper body slightly behind the trailer frame, or can lift it clear of the trailer to get a plank across, lower the front of the trailer right down and chock up the back of the body. Then crank the front of the trailer back up to level, and this will have lifted the body clear of the deck. You need to have some skids or rollers at the front of the body to slide along the deck, then before the weight of the body wants to tip he trailer back, put supports under the body and pull the trailer the rest of the way out.
Regards the lights, hanging them under the back of the frame can be a PITA. They usually end up being too low and dragging whenever you go over a speed hump or driveway crossing and getting bent or ripped off. They can also be a bit low for following motorists to see and you risk getting rear ended. Options, stick them out the side of the frame, or mount them on the hatch and have a second set, on a board, (such as the one you have in it at present) for when you want to use it as a GP trailer.
Just more things to ponder
