The string spacing is 14.5mm on the GVB 36 which is really easy on my stubby fingers and it reduces the neck width quite a bit. The other thing I have seen done by some bassists is to get a five string bass kit and put an adjustable 6 string bridge where the string spacing can be changed and a custom made six slot nut. I know that such bridges are out there but they are hard to find and a good guitar maker can make the six string nut.