Negotiating base for junior AE role? Advice please!

I started at my firm in the inbound sales role after college which was a completely new role at the time. Got promoted to BDR and received a 5K bump in my base. Then, management grew out the inbound function and started all of those reps at the base I receive as a BDR.. I’m going to be promoted to junior AE and anticipate to make the same base as the BDRs below me now.. internal HR & politics is notorious for being difficult and unable to negotiate with - any tips on how to get a fair raise here and level out the playing field?