It’s not a fashion contest, so if you want them on your bike, go for it.  My seat rack acts as my rear fender (sorry, no skunk stripe jw) and I wear sandals so I don’t worry about my shoes filling with water.

You can buy brackets to put on your front fork to connect fenders to.  It’s like a hose clamp that goes around a thick rubber grommet.  Unless you have a racing bike with really tight clearances (which I wouldn’t recommend bring to RAGBRAI anyway) you shouldn’t have any problem finding something that works.