small problem 5th wheel hitch rails

[1tonpower]

my truck in sig. SCSB with a fuel box. i have the aux tank as close to the front of the box as i can get it and still be able to open the lid all the way. the box is 20inchs wide with a bout an inch and a half between the front of the box and the tank.

my problem is..i went to install my rails the other day and im coming up short.
the rail kit im using 58058. and im using the ford custom brackets on the frame.
with these rails and the frame brackets i need 54 3/16" from the back on the bed to the back of the front rail. that would put the rail under my aux tank.

the 58058 rails are a 10 bolt design. i can go with rail kit 30124 witch is a 6 bolt design and ill have 52 1/16" inches. thats just enough room to mount the front rail and ill be able to keep my box.

now here is my question. the first rail kit when installed would put the king pin 2 5/16" inches ahead of the center line on the axle. the 2nd rail kit would put the pin only 3/4" of an inch in front of the axle.

how much difference is that that going to make on the front axle weight.
how big of a deal is this and is there any other option i can go with in order to keep my fuel tank and have the rails.

[1tonpower]

i know there are others running a short bed with a tool box.

[baldguy2001]

Are you using a "Slider Hitch"?

[1tonpower]

i will be using a slider when i get one.. right now i have "the goose" mounted to the rails. i went with 4 bolt rails with the custom frame mounts


the front of the truck is to the right....i started building the winch mount for it..theres another tread about that