Interesting that Kubota has washable filters on at least some models. My L2501 filter seems to never be that dirty no matter how much dust I feel is on me.
I washed a Onan generator filter the other day with carb cleaner. I don't think it was designed to be washed, but the residue from a bad LP fill up had coated most of it which starved it for air. Since the generator needed to work for the wife, daughter, and grandkids trip, carb cleaner was the attempt and worked. Don't worry a new filter showed up and will be swapped out.
I run K&Ns on my gasoline engines without turbos, but never on a turbo engine. Dirt is pretty horrible on a turbo according to all I've read. Also, most OEM filters on diesels are actually very good from all I've read as well.