Based on my (admittedly limited) experience doing BEAD tuning, I would go for a multi-scale option which is meant for BEAD tuning. It's probably excessive, and the reason I have a BEAD bass to begin with is because I just have a spare bass lying around, but I've really just not had much success with 34'' B strings in general. I recognize they do it for some people, and that's great, but they just don't do it for me. From the multi-scale options I have tried, it feels like that would be a better route in general for extended range basses.
A multi scale bass is a great idea but not an option right now for me.