Value is a highly relative concept as you stated. What I would do is shop for a truck like yours as though you were going to buy one. The cost to replace yours with an equivalent truck plus about 30% would be a reasonable insurance value. FYI buy an "agreed value" policy rather than a "stated value" policy. There are professional appraisers that will give you a written appraisal for a fee.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.