We've talked about split-baffle ideas variations and in the past, both in the Oddball Mic Technique part 1 tread and in various Jecklin-disk threads. I can't recall where specifically so you'd have to search them out. The discussion in the OMT part 1 thread is probably somewhere close to the beginning, as I was messing around with Jecklin disks back in 2007 or so and strongly considered the idea of split small disks (I considered using clear CDR dummy discs) before going with the DIY spherical attachments instead.
I'll summarize a few issues which come to mind-
> Size of the baffle (and microphone distance from the baffle) determines the low frequency cut-off above which the baffle becomes effective. Smaller = higher cut-off frequency.
> If mounting the mics right up against the baffle or flush-mounted in the baffle surface, it can be advantageous to use a hard, sonically-reflective baffle instead of a damped sonically-absorbent surface. That creates a small boundary mount situation above the cutoff frequency. That makes it unnecessary to try and evenly-damp the surface with respect to frequency, making the setup simpler and lighter-weight. Mounting the mic on the baffle surface also maximizes the geometric "occlusion angle" - that is, how much the mic "sees" around the edge of the baffle, making a small baffle somewhat more geometrically effective above the cutoff frequency (the baffle "appears bigger" from the microphone's perspective, compared to spacing the mic away from the baffle, where it can "see further around the edges").
> If not mounting the mic directly to the baffle, use felt, foam, wool or a combination of materials to damp the reflection off the baffle. To check effectiveness of the materials, hold the material against the baffle and place it close to your ear at an angle similar to cupping your hand to hear. Play some music on the stereo and get up close to one of the tweeters. Orient yourself so that the baffle is angled like a mirror reflecting the tweeter output into one ear. Play with the baffle angle and listen for significant change in timbre of the reflected sound. If it sounds brighter with the baffle reflecting the sound directly in, and less bright at other non-aligned angles, the damping material stands to be improved.
Raw cork will be quite reflective at these higher frequencies. It can work as a support disk, but think felt, wool blanket, or a couple layers of stuff like that glued to the cork disk. Fur as used for wind protection isn't particularly good except maybe as a top cover layer, as the intent of wind protection fur is to not attenuate the high frequencies as much as practical. You wan't the exact opposite for this- maximal attenuation within the frequency range in which the baffle is effective.
> Figure a way of adjusting the angle of the baffles on the bar, so you can play around with pointing them more forward rather than always facing directly to each side.