I think $4000 is a fair deal. To be honest, I'd rather spend $6500 for one that I could drive around that is turn-key, but I would bet that you'll end up with a nice truck for less than that...even after you figure your time into the equation. The kicker is that the $6500 deal is off of the table...at least for now. The dealer told me he could revisit the issue with his govt contact. I am not sure how he does it, but he can buy directly from the govt...bypassing GL and GSA altogether...but he has to buy in bulk.
I would be interested in the truck, if you don't purchase it. That has more to do with the fact that I would never consider paying $10K+ for an overwidth bridge truck.
I'd be curious to hear how you plan to reduce the width of the bed. I, myself, like things to be original, but I can totally understand that there are often designs that can be improved upon (see Bjorn's truck) or situations that require a modification (overwidth issue).