Crawling around to disconnect and reconnect the driveshaft would suck, even on dry surface. You'd also need to make sure no one, including yourself, decides to start the truck and put it in gear when it's disconnected. That'll make for a bad day.
Doing some additional light reading into the topic, though, I'm going to have to retract my prior opinion. The locked vs. unlocked steering got me thinking...it seems doable, but potentially unsafe. Compelling arguments read about included:
Locked wheels being a slight angle, causing the vehicle to be towed crooked.
The steering wheel lock being damaged.
Unlocked wheels being able to turn left or right, causing fishtailing.
Steering and suspension components being designed primarily for forward motion, not reverse.
U-Haul having specific warnings to never to a car backwards on a dollly: https://www.uhaul.com/Articles/Tips/120/Tow-Dolly-User-Instructions/
So, given that, while it seems mechanically possible to do what's proposed, I'd say it's advised not to...which leaves disconnecting the driveshaft as the winning option. Carry a blanket to throw on the ground, and some big warning flag to throw on the steering wheel to prevent starting (perhaps in addition to disconnecting the battery once it's on the dolly).