As you already know, the two routes into biopharma BD/management are to either:
1) work on the science end in said company with a PhD, slowly building up your BD/management skills/responsbilities. little by little, you will be come that BD person. You wont need an MBA as you have incrementally assumed all the skills and experience you will need and have demonstrated the capacity to lead/perform.
2) Apply to a company as an outsider with either a business degree and/or PhD. If the latter, you will be required to have all the requisite skill sets under your belt and be able to prove it.
I think your biggest challenge is getting into industry at all, in any context, whether on the science end, QC/QA, BD, manufacturing, whatnot. This is a significant but not unattainable challenge.
Your next big impediment is not being able/willing to move. I live in one of the densest biopharma hubs in the USA with well over a decade of industry experience, and despite this, my biopharma job search over the past 4 months is leading me to believe that it is almost certain that I will need to move to find new work.
When I look at the license plates in our companies parking lot (global pharma), I see vast out of state license plates. it is very telling.
I know several PhDs who went on to get their MBAs to transition into BD. I also know many PhDs who just gradually assumed such roles from within the inside of the organization. Furthermore, I also know some PhDs who came right into BD from external bench science. Not sure how they pulled that one off. Maybe a Nature or Science publication that made the front cover and came from a super-hotshot lab?