There is a Linux-armv7l build of Reaper, that you may be able to run. The default image to be used for the CTAG is based on the IoT distribution from beagleboard.org, so it does not have the desktop environment that you would need for it. However, there is also an image that ships with the desktop environment that could potentially be used for this. @henrix should be able to tell you what steps are needed to turn a standard beagleboard.org image into a CTAG-friendly image, so you can get the CTAG to work on the desktop image.
In all fairness, I am not sure about the CPU requirements of the Reaper GUI, so I am not sure how much CPU will be left for the audio, but maybe it's worth a try!