Find a harbor freight and get one of the blue hand trucks with the big wheels. Make sure to search for a 15% off coupon. Also pick up 3 packing blankets.
Find a roll of 80 gauge stretch wrap--18"x1500", if possible. Home Depot should carry it, but you can get it cheaper per roll from uline.com if you can wait. Wrap the game and back box in about 3 layers to help protect it from scratches.
At home depot, get a small packing box (put the foot of the game on this), and use it to protect the bottom of the cab when moving with the hand truck. The cardboard is also helpful for sliding the game around on floors.
Get 3 large packing boxes, and fold them in half. Use one in the hand truck. When packing the game in your vehicle, use them to protected the sides of the cabinet after covering the cab and backbox in the packing blankets.
Also, get 3-4 medium boxes, put them on the floor of your vehicle, and layer them so they slide over each other when you push the cabinet in. Much easier than brute forcing it, and also helps protect both the game and your vehicle's interior.
Don't be afraid of detaching the backbox if you need to. Just take lots of clear photos of each connector, and double check them when plugging them back in later.
Obviously, it's easiest to be able to just fold the game up and go, but if you don't have space, it's easier to remove the backbox entirely instead of trying to maneuver the cabinet and the backbox. There would also be a lower risk of damaging the cabinet/backbox when trying to juggle/maneuver both at the same time.