Hi,
The hardware only supports 2 "processed" streams at a time. This includes color debayering/chromatix/auto exposure/etc. This means you could set up 2 fully processed streams and a third raw stream where you're have to use a third party AE algo (we provide options already through libmodal-exposure in the latest voxl-camera-server) and either just use black and white or do your own color debayer/chromatix job.
The last stable packaged release for camera server on VOXL doesn't provide a good support infrastructure for this, but the latest on the master branch of voxl-camera-server has a major rewrite of the code that would support this almost out of the box (you'd just have to add a configuration field for which one is raw). This code has been extensively tested on all of our normal ov7251/9782/imx214/377 and is only not released because we haven't finished support for the TOF sensor (which doesn't seem to be a part of your use case).
Lastly, we've only ever used the hires cam in slots 0 and 1, so there's not a pipeline in place for the tracking camera slot, but all you'd have to do to add this is modify the camera_config.xml file in the voxl-camera-server package to copy the IMX214 block once more and change the cameraID to 2. I'll add this in our next release either way, but if you need it sooner that's how to add the pipeline.