I actually do work in a barn. Several of them in fact, as I am a hoof trimmer. Unless I have been under ten horses that day I don't generally worry about needing to shower more than once a day. But then I don't do aikido on days I have ten horses on my trim list. I find that a face cloth and some clean water are enough pre-class prep on most days.
In the summer I might take a second no soap shower to get the sweat and dust off but too much soap is bad news for the skin. Luckily I'm not a very girly girl and I don't feel the need to smell pretty. No perfumes and lotions for me which I am sure the men in the dojo appreciate. As long as I don't stink its all good. Heck some of the guys Iv'e trained with occasionally have gi that smell worse than I do after a day in the barns.