That's a really nice EUB! Congratulations!!
How did you build it? Did you use an existing upright bass neck/fingerboard, or did you build everything from scratch??
About tuning in 5ths, I am sure that would work excellently, but everything will be different on the fingerboard. So it's a new instrument all together. I play both cello and bass, but the two are radically different, and I have a hard time playing the same things on the two instruments. So prepare for some heavy practicing!
