We are going through a similar situation now, getting a 2008 F250 ready to tow a 5th wheel.
Depending on what the other upgrades you have planed will cost, you might be at a point where selling/trading your truck for a same year/newer used 1 ton might be a viable or more cost effective option. In the end, I decided to upgrade since we like the SRW ease of parking, driving etc and fuel economy & taxes, but it was tough and we almost made the move to a DRW 1 ton. I just hope we don't buy a 5er and then 2 months later decide to step up to a larger truck, I will be quite mad at myself.
I suggest you price out the upgrades and make sure it is what you want to do.
OJ
While the 2008 F250 does have slightly more capacity than a 2001, here is what we have done to prepare our truck.
Air Lift 88398 LoadLifter 5000 Ultimate Air Spring Kit with Internal Jounce Bumper $374.65
Air Lift Company 25870 Wireless One (compressor) $316.87
Heavy Duty Bilstein Shock Absorbers (Front & rear) $307.80
FRONT Sway Bar (1 1/4" diameter) $200.95
REAR Big Wig Sway Bar (1 5/16" Diameter) $340.95
These items will have to be done for almost any truck to prepare for a 5er, but some used models might include these items (or equivalent).
PullRite 0841 Super 5th SuperRail Mounting Kit - 16K/20K Load Capacity $429.17
Hensley BD3 Hitch (used) w/adapters $1270.00
5th Wheel/Gooseneck 90-Degree Wiring Harness w/ 7-Pole Plug $111.94