I had this in mind, building out my shower downstairs well in advance.
First off, I selected a brand of white porcelain tiles and added a blue glass accept strip near eye level of the same tiles I used for the floor of it and the low spot is right at one corner of the drain. The squares are one inch across and when you leave a gap of four tiles square around the drain, a number of common drain covers can be used and removed for easy cleaning.
Secondly, I bought a shower head with an extension pipe such that when the head is tilted around, I can rinse EVERY PART of the shower that is three feet or lower off the floor, making clean up easy. The only change I might make is to add a diverter and tube so I can easily fill the bag. I use a plastic container peanut butter came in to hold under the shower head and tip into my 6 quart bag. I keep a bottle with a brand of liquid soap in it for extra cleansing
Third, the shower rod is actually stainless steel pipe used to make safety rails on boats/yachts with matching flanges screwed into the studs in the wall structure. The wall thickness is around 1/16". I can do chin-ups on the bar (175 lbs) without ANY flex.
Fourth: I find regular shower curtains can stain, so I had one made from 1mm thickness natural colored latex sheeting (a nice kinky touch that doesn't make for awkward questions when people sue this bathroom) with black pinstrips and stainless steel grommets. With the curtain the same color as the bag, I can leave it there and not attract any attention.
If anyone has interest, I can post pictures here of it.