Lack of fenders is a real nuisance. Mud and water constantly being thrown on me, especially on my goggles and camera lens.
I was hoping someone else would find something that worked and just copy, but after nobody seemed to find anything I decided to try and find something myself.
Finding a suitable front and rear fender has been a problem for me. There seems to be practically no dual crown fork fenders out there. Any that would fit in the steerer tube I think would get crushed if you bottom out the fork by the fork brace.
I found a good solution for a front fender that worked perfectly and did not allow any water to hit my face when testing it. Normally, just the slightest bit of water would have my whole front covered.
A cheap solution that works very good is a muckynutz bender fender XL. http://www.muckynutz.com . This should be all you need for a front fender. Fits easy, has no weight, and you can still see most of your front tire.
Rear fender is more of a problem, especially with a motorcycle seat. I looked at dirt bikes to maybe find a solution. I ordered a rear dirt bike fender for $20 bucks to play around with. I zip tied it temporarily to the motorcycle seat to see how it would work. When testing it today over a really muddy and wet area it was not long enough and the muddy water got around it. It seems I will have to add some kind of extension to the end to get at least 6 more inches of coverage.
I kind of like the dirt bike rear fender as it looks good and if I can modify it and mount it better with screws, it would work really well. I will try and find something to extend the length somehow to get more coverage. Seems like you really need a fender to go past the end of the tire to stop mud from coming over on your back. Even with bicycle seat tube fenders, they all seem not to be long enough.
I also got some hand guards for the bike. The main reason was to keep the wind off of my hands as when the weather gets in the 30's my fingers start to go numb and I have to stop riding.