Another DW who is the messy one, though for me it's also frustrating because I feel that DH wants it cleaner but also doesn't want to be the one to do any work to make that happen, and that I'm supposed to be responsible for everyone's messes, not just my own.

But beyond that I think the designated space in the house for his mess is a great idea, or alternatively what we've done is to have a 'clean' room.

And one other point I'll make is to just point out he brain difference. Lots of people mention that they can't think in a cluttered house and that it makes them anxious. Personally I'm actually the reverse - I feel anxious in a space that is TOO neat and orderly. A little bit of clutter / verbal noise is actually calming for me. I am the same way aurally with studying / working - I need a bit of noise to focus.

I'm the messy one in our marriage (I'm the DW). DH isn't a super neat freak, but neater than me. So he just walks behind me throwing away empty ketchup packets I left on the counter, closing kitchen cabinets, etc. (Yes, I have ADD)

I'm lucky that he doesn't nag me. Every once in awhile he gets mad, but not very often.

My Mom had this HUGE basket or Box. Once a week should would go around the house and put all my Dad's stuff in it. Dad could always find it because it was in the box. Once every 6 months or so when the box got full, Mom forced Dad to empty the box.

My husband is like this too, although perhaps not quite as bad as yours. When we moved to a house where he had his own personal space (his own office, separate from mine), I started gathering his clutter from the rest of the house every day, depositing it in his office, and then closing the door. He didn't have to clean up his mess if he didn't feel the need, but I didn't have to live with it either. He loses things more now, I admit, but that's on him for not taking better care of his stuff.