How much clearance do you have between the rim and the pads? I have probably 2 penny widths on each side of my canti-equipped Outlook. It would be less than that, but I had to give myself enough room to squeeze them together to unhook the QR cable (I have QR wheels front and back on it, which I often swap on a whim)
If it weren't for me swapping rims, the clearance would be even tighter. The wheels are almost perfectly true, so I could have the brakes pretty close to the rim.
is it possible to get them a bit closer to the rim without dragging?