I used quite a few different techniques on this bathroom, starting with the walls -waterproof vinyl sheeting is probably my new favorite method.

It doesn't have all the seams of a snap-together wall tile system. It's MUCH lighter weight. It can be fastened securely with PL Premium. Looks just as good.

Second, I made a custom shower pan from plywood that integrates a slope to the drain, plus a flat platform for the toilet all in one. Coated with fiberglass resin for waterproofing. Shower pan is coated with mold preventing "Perma white" paint. This shower pan cost in total about $60 vs premade shower pans that run upwards of $300+. This method can be replicated for ANY dimensions so you don't have to rely on premade dimensions.

Im also using composite decking boards for the shower floor that will never get moldy or rot.

The bathroom is larger, allowing for a residential size-toilet. Much more comfortable.

I integrated a recessed medicine cabinet (again, residential) into the opposite wall for storing all toiletries.

Recessed dometic waterproof toilet paper holder.

Finally, I went with a recpro retractable vinyl bathroom door. Works better than a standard door against water, and can stay open leaving the entire space feel much roomier (and also brings in the aesthetic of the bathroom into the rest of the space.. when it looks this good, why not?)