Thanks for the replies, I mean that I see millions of modified bikes with this kind of filters and no fenders. I don't intend to ride when it's raining but specially in Finland where i come from, you never know when it's raining or snowing, so, for those occasions I am looking for a solution. This rain sock will definitely be an addition to my riding gear, also for myself if I can find a bag that's big enough.
What comes to fenders, I have a small fender to the front end but I guess that's just small enough just to improve(?) the looks.. For the rear I think a plate can be added to the frame behind the air filters. The decent airbox is one good option, but it has to be self made as I haven't found an aftermarket solution for that. It's not a problem but timewise this summer will go with this setup.. Do you know if there are some aftermarket boxes?