8 string (octave's) bass nut width question - need help

[Eric Schmitt]

I'm in the planning stages of an 8 string short scale bass build; 8 string as in having octave string like a 12 string guitar. I'm wanting to model it after the dimensions of a Hagstrom HB-8. Looking up the specs on that bass it says on their web site that the nut width is 40mm. I have a 4 string bass with a 40mm nut and trying to picture octive strings on there it seems like it would be a pretty tight fit. Unfortunately no one I know and no stores have an 8 string bass that I can make comaprisons to in person so at the moment I'm having to rely on what I can find on the web.

My questions are:
Do yall think maybe the measurement on the hagstrom site is the string spread instead of full nut width?

Would 40mm width be fine or would it end up being too cramped at the nut?

If 40mm would be too cramped what would be an acceptable nut with to use?

[Bob Gramann]

Do some trial life-size drawings and see what makes the most sense. Bass strings can have pretty wide excursions, so I would worry that the paired strings would clatter together if they were too close. You may have to do some experimenting, maybe mocking up a pairing on a board at your scale length.

[David King]

I've only done one 8 string and it was quite a while ago. I used my standard 5 string neck specs which are 43mm at the nut and 72mm at the 24th fret.
It came out pretty well though I had my doubts at the time. The owner uses it as a 4 string and it's great at that.

[Art Davila]

I had a friend with an 8 string hamer and its neck was as not any wider than his 4 string to my hands atleast.