Have a look at this guy; Zander Zon...
Admittedly, he uses 'Piccolo' strings on his bass which gives him some significantly different tuning options including getting up into guitar octaves however, it's how he combines his tunings plus his wonderful talent that enables him to play some truly beautiful music.
Enjoy:
https://www.youtube.com/watch?v=YjGKM6VFJ-s