Can this be done? Emergency compressor (release brakes)

Sure. If it's tight enough to hold air that well. To move a non-running truck around the yard I've hooked up an electric shop compressor to air it up and move it. If you have to use any brake, it's going to run out of air fast. And an air-ride suspension will use up some air pretty fast off-road.

 

You can "cage" brakes. To protect me, ask a mechanic. If given enough time in theory will work. Most will release @ 60-85 lbs. If there are no air leaks.

 

I carry one of them in my car and it takes forever just to fill a low pro car tire. I think it would get hot and die before it put enough air into a truck system.

 

I remember seeing a device years ago that replaced a spark plug with a hose adapter so you could air up tires with the engine. No idea how it worked without filling the tires with gas. Maybe that's why it's not on the market anymore...

 

I suspect every other component in the air system would fail before the compressor ever packed it in.

I once used a brake line that ran from the frame to the front brake chamber to replace the ruptured coolant line that ran to the compressor head on a 3406.

 

It still on the market for motorcycles...but it takes a good 15-20 minutes to fill a bike tire. Short hose, havn't seen one for cars.
I have an air compressor meant for rv's, it's supposedly good to at least 150 lbs, but to get to 90 lbs took awhile...no tank. But from Camping World it was about $300. marked as Air Lift Heavy duty Air Compressor.

 

they worked too good and never broke so they stopped making them so they could sell lots of those useless plastic ones. I'd buy a few if I could find them!

 

Highly illegal and a very bad idea. Caging the spring brakes is only for mechanical work, not for moving the truck. What happens when you run out of air, you can't stop!