My company provides towels and a body wash/shampoo dispenser. I kept (I am closer to work now and shower at home) toothbrush, toothpaste, deodorant, and razor at my desk. I never bothered with flip flops. When I got to work I'd unload my clothes, grab the toiletry items and carry everything to the shower. The shower is in a larger single person room with a toilet and sink, so I'd just put all my stuff on a bench.

Paul