[QUOTE=JohnDThompson;16853206]In general, it should work. Get some BMX chainring bolts to mount a single ring. Often, the best chainline is obtained by mounting the ring on the inner plateau. One caveat: if your "Record" ctranks are actually "C-Record" you may have trouble with the mounting bolt that goes in the back of the crank arm, as it is different from the other bolts, but perhaps a spacer might allow it to work...[QUOTE]

+1/2

A few issues to consider.

1- Campagnolo cranks are 135BCD, so your options will be limited to Campag. rings, or analogs made to fit. I don't know of any 135 BMX rings.

2- if they are Record, you have to use the special bolt that mounts to the arm, but can use track or SS chainring bolts for the other 4 positions.

The special bolt will need a 4mm spacer to replace the missing ring regardless of whether you mount the single ring inside or out of the arms. If you don't have a spacer, and are willing to sacrifice a ring you can cut a bolt hole off either ring.

Or you can do something slick, and cut, grind or file all the teeth off the outer ring, then file a bevel on the inner side so it's like one side of a V-pulley. This way it'll make a nice chainguard, and also a safety to re-rail the chain if it wants to fall off on bumps.