Back in the day, when I needed to change the fuel pump on a longbed Toyota by myself. I took all the bed bolts out, except the back two, and just ran those out till the nut was at the end of the bolt, but still using all the threads in the nut.
Pried the front of the bed up enough to get a 4x4 wood scrap between the bed and frame. Then slid a scissor jack in there, next to a bed floor brace, and jacked the bed up as high as it would go. Braced it up with more wood, and had plenty of room to do the fuel pump.
Sketchy? Probably, but it got the job done.