Hi Ozzie, understand where you are at as that body is H U G E ! ! !
After doing the J Bass a while back it got me thinking about rounding off square edges, more for comfort but also for aesthetics too. On the Swampy Tele I purposefully dialled in a more Strat style rounded edging and it looks and feels great. Can't wait to finish re-finishing so I can put it all together and start playing.
With the neck seating on your Behemoth from memory the Bass neck's bridge placement is not pre-determined however on the 6 stringer side of things it looks like the post holes come pre-drilled. This suggests caution is required to avoid compromising scale length and end up with intonation issues. Looks like there is some overhang past those 22 frets on each board which should help cover up things at the deep end of the neck pocket.
When is the "Stork" due to arrive at your place? Bet you are dying to see your new baby, err, umm,
guitar kit.