They are about 67 pounds. What I did was put the battery into the box, and then lift the battery and box into the compartment, and set it on top of the strap that was already screwed down to the bottom of my storage compartment, and ready to accept the battery box. The box is only about 1-2 pounds, so does not significantly add to the battery weight. And you do not need to position the battery over the box inside the compartment, then lower it safely into the box.
In other words, hire a teenagers who is willing to work for a few bucks. Find a strong one, like a football player or something!
Good luck,
Fred.