Hard to comment without a more detailed description. There have been various attempts, from time to time, to fill gaps and it's difficult to define gaps. I think the Signs of History has done it quite successfully, though I've not submitted much there, so it's hard to say. I think a category such as you are proposing may end up looking like a gerrymandered congressional district, with boundaries difficult to define, but I'd like to see exactly what you have in mind. I mean, we can't leave these place unwaymarked, can we?! They need a home. Maybe the uncategorized waymark is the route to go; I don't know. Not convinced on that one either.