Fifth wheel placement on a long WB tractor

Well dont know what to tell you, that's getting out of my experience, other guys can help you more. Someone mentioned air weighs on board scales. They do work well. That I know first hand.

 

I've noticed a lot of the fuel haulers with overweight permits running with their fifth wheels pretty far forward, I'm guessing to move some of that 100K onto the steers...

 

My W9 is 310 in wb and is 13500 on the steer full of fuel bobtailing. I have zero trouble keeping it legal when loaded.
My FLC is 305 in,and when I bought it with the log gear where it was I only had 11,500 on the steer when I was maxed at 38,000 on the tandems, I moved the log gear and now it is 13,000 give or take a 100 pounds when I am maxed, so no trouble at all after I moved the bunks.