Another option for a (crude) rear fender is to use the rack and add a piece of thin black plastic sheet to its under side, on the 2 ‘lower rails’, and extend a bit backwards to avoid ‘devil tails’ 
up you back
Another option for a (crude) rear fender is to use the rack and add a piece of thin black plastic sheet to its under side, on the 2 ‘lower rails’, and extend a bit backwards to avoid ‘devil tails’ up you back