What about the cogs and the derailleurs?
And if it rains 3 days in a row?
On my route my bike gets incredibly dirty in just one ride in the rain.
My solution: Power washer. Mud caked to clean in 30 seconds.
I do run with significant rear lighting always, so when it's raining I am OK already. A MagicShine tail (about equivalent to the AA Dinotte rear light) on steady, a Knog Blinder 4V on slow fade/pulse and a Cygolite Hotshot on rapid pulse is my current rear lighting strategy (plus a reflective vest)