Showering at night is better than the morning - go to bed clean, wake up clean enough, and it keeps your bag cleaner. I can't stand going to bed with road dirt and sticky sunscreen and sweat on me. Therefore, I strongly prefer camping in campgrounds with showers. If that's not available, sponge baths are a poor substitute but better than nothing.

Also, morning is absolutely the best time to be riding - light winds, light traffic, cool.... I wouldn't waste the best part of the day showering - I get on the road as early as I can.

I wash my bike clothes every night and dry them on the rack the next day. I don't care if people didn't bathe daily for millennia, I like to be clean and wear clean(ish) clothes. It's not that I care what anyone thinks I smell like, it's for me.

I care enough about this that I don't stealth camp unless there is no choice. In months and months and months of touring, I've stealth camped maybe twice, camped with out a shower maybe a dozen times.

I used to live in a van, and was able to shower way less frequently - because it wasn't under my control, it wasn't my van - and that was a source of much dis-satisfaction for me.