Tom, Steel Eagle makes their own but puts other labels on their machines like Alkota.
Whisper wash does not make those in the picture, they look like it but the swivel is not the same and the handle is a lot different but I could be wrong, I think it is another company out of Florida. Whisper Wash puts other labels on their machines like Mi-T-M and a few others that I cannot remember right now.
Whirl A Way usually has large horizontal cutouts in the bottom of their brush skirts, the way the handle attaches to the deck is different from Whisper Wash, the handle goes in between 2 pieces of metal that is a mounting bracket bolted to the deck where the Whisper Wash is almost like those white surface cleaners, a solid block of metal round stock that has a slit cut out that goes on either side of a plate that is on the mounting block bolted to the deck but on Whisper Wash, the aluminum round stock is a lot longer and the handle is a little bit different. All their swivels are the green/black swivel that you change out the cartridge inside in less than 10 minutes now instead of pressing bearings/seals off then new parts onto the shaft.
The Steel Eagle deck is a lot taller but does not have a brush, you can order one but it is not the same as the Whisper Wash or Whirl A Way, it is a lot softer and not meant to be used like a hover deck, you would have to adapt a Whisper Wash or Whirl A Way brush Skirt onto it. I think the skirts are about $75.00 for the Classic (19" deck), not sure how much for the larger decks. Most of the weight is the metal handle and brackets to mount the tires on the back. They went to a larger diameter steel handle a while back. You can have an aluminum handle made by your local welder, take them the steel handle, buy the aluminum pipe and plates and they can probably have it done for you and that would save a lot of weight.
The Whisper Wash makes a 24" floater and I hear that it is a good machine, they also put castor wheels on it if you don't want it to float but a good feature is that the handle folds up over the deck so all the room you need to store it is just the size of the deck, you can probably put it behind the seat in most vehicles. They have a video on youtube showing how to change out the swivel cartridge:
Whisper Wash series 3 swivel