Get a 30 gallon plastic garbage can for the fish. Cheap at Wally World, under 10 bucks, closer to 5. Duct tape the lid in place, cut a 1 foot circular hole in lid(reduces spillage in case of hard braking or quick turns) Remove all or nearly all the water from the 55, even 3 inches of water can cause a burst seam if you have to brake hard or turn quickly.(Been there, done it, put me in a towering rage.) Don't put more than 20 gallons in the garbage can unless you like hernias. Spills less, too. Secure the can! You don't want it tipping over, and it will, if not tied in place.
Zeolite can be used to prevent ammonia buildup during move. The only time I use it is to ship or move fish/emergencies, it's awesome for that.