My deck is 9' long and I have the TC on all of it except 3.5" due to the water fill door. Even though I can remove it once unlocked with my modification to the hinge, I still need enough room to get the key in place. If you find a headache rack that is only as wide as the cab (verses mine which is as wide as the deck), you will not have this problem. The rear wings on the TC are narrower than 8' on the inside - Having the rear of the deck taper in will help. Without that taper, you are limited to 8.5'.
Pushing the TC back farther does change the CG and requires you use a longer SuperTruss. I could get away with a 36" SuperTruss but have 42" model so I can open the cargo tray fully while hitched to my trailer. I did not want a vehicle any longer than it need to be. If I had chosen the Ford F550, I would have the extended cab rather than my four full doors on the Ram.