So, this story starts out as so many others... with this thing I bought on ebay:
15000 grit whetstone for fine honing. 2" x 6" x 16" | eBay
...snip...
Option 1.
Cut it into (8) smaller approximately 8"x3"x1" hones and sell the spares.
Option 2.
Cut it into (4) smaller approximately 16"x3"x1" longer hones. My theory here is that the extra lengths would cut down the normal honing time in half thanks to the extra run out. I don't know if it would still take as long or potentially longer to break down the grit into finer particles to reach the higher grit ranges on slurry.
Option 3.
Keep it the way it is and buy the biggest DMT they make to try and lap it flat properly, under running water, of course. I can use it to hone my replica Conan the Barbarian sword... not.