OK ... I had a little bit of time to check on a few things
First off, MM is utilizing the non-ear pickups on their 5-string Stingrays as can be seen here
specific for the neck, the EBMM site lists these specs:
Scale Length:34" (86.4 cm)
Neck Radius:11" (27.9 cm)
Headstock Size:Only 9" (22.9 cm) long
Frets:22 - High profile, wide
Neck Width:1-3/4" (44.5 mm) at nut, and 2.75" (69.9 mm) at last fret
compare this to the Warmoth D5 neck with a similar fret count and 2.906" (74mm) heel width, and it looks like you're going to be able to just support an 17mm wide bridge spacing (the added width of a W neck will support a 17.5mm spacing).
NOTE: It would be good to get W to measure the length of fret 22 for you, as the difference in dimensions may be solely on where the measurement was taken (W = end of neck, and MM = length of fret) There is possibility that both necks have like dimensions, and therefore the MM neck sports a 17.5mm (.689") spacing
but ... you're building a bass, and not retrofitting a MM. :icon_biggrin: by looking at the EBMM image you can see that there's some extra spacing between the outer strings and the pickup pole pieces. with this in mind, it appears you can fully support a 17.5 mm spacing on the bridge, and quite possible even a 18mm spacing as well
for a bridge, you're looking at a Leo Quan BA Bass V bridge (it's 5-string) and not a BAII bridge (it's 4-string). the BA Bass V will support 17mm - 20mm string spacing, and BestBassGear.com has them in chrome for $95. you're going to need to slot the saddles, but this is doable with a little guidance, some _very_ accurate measuring, and a couple of small files.
an alternative would be to consider something like a Hipshot Type A bridge with your preferred spacing. BestBassGear.com has these in chrome for $107 (alum block) and $121 (brass block) I find the Hipshot to be significantly more user friendly than the Leo Quan, especially when you consider that there's no saddles to slot (and have to buy again if you goof on your slotting job)
all the best,
R