Welcome to the forum.
Were not all rude members here so read past those type comments .
Looking at Fords
https://www.fleet.ford.com/truckbbas/topics/2000/specs.html specs for your '00 model truck shows the F250 has a 12900 lb tow rating for a 4wd and a 13300 lb for a 2wd with the 6 speed manual. No doubt the F250 can pull that and more but its issue is the 6084 RAWR which includes tires/wheels and rear spring pack. Adding 5000# air bags doesn't help unless you upgrade the tires and wheel also.
250/2500 size trucks have had a 6000-6500 RAWR for the last 20-30 years. The F250 crew cab may weigh around 3000 lbs on the rear axle which leaves around 3000 lb for a payload. The trucks front axle carries little to non of a 5th wheel trailers pin weight so the rear axle is the big player.
The F250 isn't a good match for a trailer that heavy unless you upgrade tires/wheels and rear suspension.
Also if you haven't operated the ZF6 6 speed manual tranny in a truck you better drive it first as the tranny isn't like a manual in a car.
I have the NV5600 6 speed manual in my '03 2500 Dodge/Cummins. I find the 6 speed manual behind the low rpm Cummins shifts smoother than any of the '60s/'70s muscle cars I've owned. Drive it first.
