You are right, in the world of race cars and hot rods, you can expect to recover about 25-30 % of your investment. It is wiser alot of times to take it apart and sell. I to do not think you will get anymore for your truck with the add-ons. I know if I were in the market for a diesel truck, I would not look at or buy a diesel that had many add-ons. I would just figure the guy ran the hell out of it and now wants to pass it off on someone else. I have certain rules, like never buy a 4X4 from anyone under the age of 30. Never buy a used motor cycle or atv that is less then three years old. Never buy from anyone that describes the item for sale as "like new", "better then new", "perfect shape or condition". There is no like new, it is new only once and that was the day you drove it home. Anything for sale is not better then new, and it would not be for sale if it was perfect. Know one ever gets rid of something that is "perfect".
I think it would be pretty smart to take off the items that are fairly easy to remove, and sell them separately. When I traded a truck in that was heavily modified, I removed alot of the easy stuff, and in the owners Manuel I left a note stating" if you would like to know more about this truck, call #" Well the truck sold the second day on the lot and the new owner call. I ended up selling him most of the stuff I removed, and he got the low down on the truck, worked out good.