If you get replacement fuel pump assembly then you will know how high it needs to go, so you can pull the old one out and put the new one in.
But, I would remove all the bed bolts and filler to bed connection and try to slide the bed back, tail light wires may need to be unplugged that varys by year.
The fuel pump access hole is very close to the back of the cab, so you just need to slide the bed back enough to work between bed and cab.
Short video here: www.youtube.com/watch?v=sNpYCDDwpk4
2006 may use a two hose filler/vent vs the one hose as shown in the video
For the bumper, it depends on the bumper you have but you should have the clearance to lift and slide it