Just a mention here about strings that could be used for BEAD tuning; my son bought me a set of LaBella DTF / 760 FM (FM = medium gauge flats) strings back in October for my birthday. The string gauge is .049, .069, .089, .109. In a flat wound, this is a quite heavy gauge. I put these strings on a PBass and they were way too heavy / stiff for me. The stiffness of the core wire is significantly noticeable for these strings.
Out of curiosity, and in an attempt to get some use out of these strings, I tried these strings on a few of my basses tuned to BEAD. They worked well on my Sterling by MM SUB Stingray. The E (B) string wasn't too floppy to play and the other three strings were even better. This didn't require any nut modification at all and the overall set up was as if I was using standard tuning / common strings, nothing abnormal.
So, those planning to try a 4 string tuned BEAD should be looking for strings with a very stiff core wire as an alternative for very large string gauge.