I use a designated and labeled Nalgene bottle with the wide mouth...
As as far as using my annex. That's where I have my Eccotemp L5 shower system hooked up, and I use one of those big rubber restaurant kitchen mats to stand on when I shower...
I am debating on selling them. There e several RTTs that could use them. I also have another item of RTT use. I just need a little time t sort things out for them