you could also go for a 40 X 200 mm Belgium Blue Whetstone, it is thin, doesn't cost to much and it is long so you can make longer strokes which should make some difference.
there is also the La pyrenee glued to a BBW but they are sold a bit wider at 50 mm (I haven't used these myself)
I would still recommend you to get the Chosera and put it on its side if you realy want a thin hone, but if you are dead set on a natural bevel setter the La Pyrenee could be your hone