I have used a SnowEx tailgate spreader before. These as a matter of fact:
I added a hitch receiver hanging under the back rack so the spreader has a hitch to slide in. All they need is 12v to operate. It has a key fob remote for off-low-high settings. Its not too high tech, but it worked really well and could be used in one of our trucks if need be. I took pictures, but I cant find them to post them.
I have one new one left, in the box if you are interested.