the only time i've ever payed for a shower was at a marina on lopez island when i was a kid. i'd never even seen a pay shower before that and the only ones i've seen sence have been in truck stops. in canada pay showers are pretty uncommon. and if you happen into a truck stop smelling like a sack of sweaty assholes one of the trucks will usually offer you one if you make small talk. but ya like IBRRHOBO said there's a million different ways to get free showers you don't need to pay for them. and if you've a seasonal traveler rivers are warm in the summer so just carry a bar of soap around with you. good luck man and safe travels!
Yeah, I just took my first stream shower last week at slab city. It was interesting.. it's stream water but you walk into a concrete pit so the stream water is pouring about face level kind of like a shower. I guess all you do need is a flowing stream you can get into and it's all good. I can totally see someone giving me crap about polluting the stream if they see my bar of soap.