Two things if I may.
-The requirement for takeover and how bonuses apply is pretty straightforward. Adding complexity it as you indicate here will just open an can of worms for usability and headaches for WB around something that already works as is.
-Second and sorry to say but is delusional to think changing SOP requirements would help the littles to lock big seats. Big teams would find a way, worst case seats will just be sitting locked empty for weeks at a time. The SoP requirements won't help you if you and your team can't properly defend a seat.
Better to focus on how to grow your account, your team and improve your strategy.