Having had outside showers on 4 different rigs over the years I have yet so see the benefit. The only thing I've found them good for is washing the dog. Although according to some on RV boards you'll go to the federal penitentiary if you use it and get one drop of soap on the ground. In the least you'll damage the entire ecosystem.
The one we had with the slinky hose and quick disconnect simply had a standard 3/4 garden hose connection on the business end. Not really an outside shower per se, no hot connection cold only, more like a dog hoser than anything. Pretty easy to adapt some type of handheld shower head to the 3/4 hose connection with some off the shelf fittings.