I fabbed up a cardboard mockup at Christmas when I first thought about running road wheels on the Bonty. The mockup looked like it might work so I bought some 1inch x 1inch aluminium box section.
I made one rear adaptor plate first and it worked. It flexed a little and the brakes do take some time to setup due to the finite spring tension adjustment (moving the pads further up amplifies the V Brake spring tension adjustment, and the cross top levers aren't supposed to work with V's)
The more I thought about the fronts the more I realised the wheel force moved the plates through a different direction so they didn't need as much 'plate' on the surface of the original V Brake. So I reduced those down a little.
Overall they work pretty well, they aren't light (big fixing bolts required)they flex a bit and they are a setup that is either perfect or very wrong. I'll run them on the rollers for the rest of the winter and then come spring/summer I'll try it on the roads.
If they prove to be a bit lacking on the open road (I live near some bigs hills) I'll look into road calipers mounted on custom braces fixed to the canti bosses.
Black 105 calipers mounted on bright white painted, Shimano branded, custom braces maybe