I would research with another dealer. Try to find the biggest baddest busiest one in town. My guess is that if you replace the mirrors, they can actually re-flash the modules in the vehicle to accommodate for the new ones.
Also talk with some sales folks. Sometimes people want the big truck, but won't buy it due to the "tow mirrors". They may actually be willing to have the service dept do a swap for both of you.
In any case, it can't hurt to ask. Most of these vehicles are customisable, but only if your order them and wait. The dealers just get ones with certain features and then talk you into to something "close enough" because they want to make the sale that day.