Hi and thanks for your news ...
I had a remark on the picture of the bass. may be I am wrong but it looks like an alto (violin) I wonder if the tuning pins are that large in a real bass, the global shape is also a tad different !
For the measure bar If you can have a visual spot that is accurate enough that should be nice , a simple red light on 1 or 1-4, whatever,
Even if it is not always precise one can use it whenever he is not sure of the "one".. after a few measures even with delay or some timing errors it can help. (I guess up to half a beat error should be OK as long as the idea is to find the clave orientation)
Just my opinion
Have a nice day (it gets a tad cold here in France !)
Isaac