I normally pre-mix my fuel and carry the extra fuel along. I also made a small spreadsheet that I printed and laminated and stuck under the seat to give me the correct ratio.
Are you talking about the stock filter? I washed mine in fuel when it was still stock, but have since replaced it with a K&N, for the K&N, I use the K&N cleaner. To answer your question, no I don't recommend it, fuel is dangerous and can penetrate your bloodstream etc, ect, ad nauseum.
You should be thinking about upgrading that filter if it's still stock, it's going to let you down.