Its not an exact solution, but a significant improvement over QR all together in terms of stiffness.
When I built up my Pacenti SL25 for my Boone Disc 5 I picked up on Ebay I bought hubs from BHS (Bikehubstore) and one of the options with the Bitex hubs was a 9mm and 10mm thru-axle end caps that work perfectly with DT Swiss's RWS Thru-bolts.
They function and look exactly like a Thru-axle except they fit into QR dropouts and function very similarly to thru-axles.
The problem is finding hubs that support the 9mm/10mm RWS system. You could hack it with an appropriate sleeve or if you're handy with a mill, maybe shave it off to fit...
You'd have to do some research to find out if this solution works for you, but this solution does actually exist.