As far as building your own, there's any number of adjustable spacing bridges to be had, and blade-style pickups would cover the eventual spacing, so you wouldn't have to worry about the strings lining up over pole pieces.
I have five 5-strings that run the gamut. The two Alembics are their 'classic taper': 2 nut by 2.5 at the last fret. I have all three versions of the Yamaha BB5000. The first two were essentially made by taking a bb3000 4-string and subdividing for five strings, so they're narrow by today's standards (remember, these were the first production modern fives, from the mid to late 80's): 1.75 nut by 2.25 last fret. The third 5000 is AFTER all the thumb/slap guys started being 'girly men' about a narrow neck: 2.75 nut by 3.75 last fret. BIG spacing, like most modern TRB's and others.
I play all of them over time. I like the Alembics best, as the strings are almost parallel, not much flare at all. The narrow 5000's (think spacing like a Ric) remind me of fingerpicking guitars, and I really like them, the only rub being playing right at the nut: It really tightens my technique since they're REALLY close together, so that's good. The 'big' 5000 is like loose jeans, it's comfortable in a big floppy way. It stretches my hands, especially reaching over to the E and B. On the other hand, it's easier to play at the nut as they are further apart.
I like them all, but narrow is just fine with me. I feel like my technique must be better for them being more narrow, and it's a breeze to play. Yamaha gets crazy with the fingerboard width on their sixes: The TRB6's/JP Signatures are just crazy wide, like some others.
I worry more about a thick, baseball bat, round neck (original Steinbergers come to mind) than width or spacing.
Best of Luck,
J o e y
