Mileage? If its average for the year, (60kish) i'd say the truck is worth about 13k if you sell it private party. To the right buyer, the mods could ad some value. 17k is way too much to be asking, in my opinion.
10k trade in i'd say is fair if you want to go that route. Most dealerships are going to stay away from it simply because of the mods you have done to it. You might be able to get a bit more if you sell it straight out to a privately owned dealership instead of going to Ford/Chevy/Dodge dealer.
Otherwise, like you mentioned, the mods won't add any value to the vehicle. To 90% of the buyers, the mods you have on it will be a negative in their book. It could even decrease the value of the truck overall. You just have to find that right buyer.
But overall, I say keep it. You've done a lot of work to it and you should enjoy it now. Ask yourself, do you REALLY need it? Would you enjoy a fullsize that much more? And please, don't go the Taco route. Way over-priced.
I dream all the time of getting a fullsize 4-door or a diesel. But then I realize I don't need either of them, and i'm happy with my Ranger. Although, I do have my Bronco if I ever really need to haul more then two people.
TOTALED DEC. 2014...05 XLT 4x4
Replaced with Blue Jean Metallic 2014 SuperCrew F150, 5.0 Coyote, 10% tint, Hell Bent Steel Leveling Kit, Allied Duals, Weathertecs, Uniden CB