I have a set of trekking bars, and could only get the mtb brake levers to fit on the part of the bars that would be closest to you (in the Sheldon Brown pictures). So, this led me to think of using a set of road brake levers which are compatible with V-brakes (Cane Creek, Tektro, and Dia Compe all have some). As mentioned above, the difference in diameter poses a problem.

Wouldn't a shim of some sort work? I know that MTB levers and shifter clamps won't work on road bars, but I don't know why road brakes or shifters wouldn't work on the smaller MTB compatible bars. Isn't it only 1/16" (7/8 vs. 15/16)?? I've seen pictures of aero bars clamped to MTB flat bars, so I'm sure they used a shim of some sort.

That being said, I would attempt to mount them on the outside portion of the bars. That is where I would be holding the bars most of the time. Thus, making the brakes more readily available.

As far as using an inline brake . . . one question: are any of them compatible with V-brakes?? I'm not aware of any, but that doesn't mean that there are none available.