I’m really fascinated by the idea of violin with just percussion, and I think I may have found the perfect percussionist. He is, of course, extremely busy—good (excellent) for him.
In the meantime, I downloaded this wacky metronome software http://bouncemetronome.com, which can play polyrhythms, any time signature you like, change tempi—you name. It can even slightly adjust the tempo of the rhythm you are working on, which is a great exercise for following rhythm precisely.
The example uses a lydian dominant scale on one of the metronome’s African rhythms. Note how it fluctuate slightly in tempo. I discovered, after a few tries, that long sustained notes work well over complicated rhythms. Not the only way to do it, for sure, but it allows the rhythm to come out and the violin to float on top.