Handwashing the shorts while you have a shower after the ride home is something I started doing when I do longer rides. I use a natural olive oil soap for all my showering and it works well on the bike shorts. I haven't chaffing problems but I either go commando in plain clothes or just wear the regular tight chamois-pad shorts. This has worked for me for distances from 0-50km. I'm not skinny either, probably back to 220lbs now.