It wouldn’t be cheap, but here is what i was thinking. You know the Pro Mechanic bike stands that you put the bike on without the wheels? Somehow remove the part that holds the bike and mount that to the wall vertically. That way the bike would hang from the front dropouts and the BB would be supported by the stand against the wall.

Not sure these stands come apart like that, and no idea how you would mount it, but just figured i’d throw it out there for an idea.

Hopefully you know the kind of bike stand i’m Talking about, i tried to post a URL, but i don’t have 10 posts yet.