Hmm, 4 keys left of space and 5 to right is a really specific requirement. My Filco TKL JIS(Japanese Layout) has this and I made it fully reprogrammable using the Pegasus Hoof from here: http://bathroomepiphanies.com/controllers/
It's one of those "I wish someone else solved this so I could spend my money on it vs. my time"
Thanks for the suggestions tho!
It's clearly possible, but nobody does it yet. I considered building my own board, but now I'm leaning modular. Thanks for the suggestion though, it's helpful to illustrate how "close" so many keyboards are and the obsession us KB nerds have.