Alot depends on your budget and what floor plan meets you needs!
A DP will cost more to purchase, fuel is higher, maintance is higher. The inspection sticker is only $15.00 vs the $35-40 typically on a gasser. You will also need a Class B license here in TX.. Don't let that keep you from a DP, it is easy to acquire.
What you get in the DP is a better ride, more storage, stronger chassis, air brakes,6 speed xmission, longer engine reliability and an engine that is 35' behind you versus setting between you and the passenger. That makes the gasser noiser and hotter in the passenger compartment. The 5' difference in length may not seem like much but trust me it is a huge difference. You will also have more towing capacity with the DP. I don't think there will be a great difference in fuel consumption with either one. If you think your useage plans may change in the future, I would lean toward a DP. If you feel that your current useage will remain the same for a number of years, than a gasser will work fine.
I do most of my own maintance on my DP so changing filters, oils etc is not that big of an issue for me.
Don & Bunny
06 Saturn ION toad manual 5 spd