How about something like this. It looks to have a pass through from the cab to the box. Biggest down side is everybody will want you to help them move.
2018 GMC G3500 for sale - Lake In The Hills, IL - craigslist
2018 GMC 12ft Box Trucks - Box Truck Liquidation Sale! Price: Call for Pricing Description: USED BOX TRUCK LIQUIDATION SALE! DO NOT BUY A BOX TRUCK UNTIL YOU TALK WITH US! If you're in the market...
louisville.craigslist.org