The BMP is far more flexible and covers a lot of very different things in it right now relative to other buildings. Especially most pioneer buildings. So I’d suggest splitting it into two buildings. The basic materials plant, which mainly refines raw resources, now makes PE, MCG, I, MG, and SEA. Its new counterpart would be the Factory (FAC), which produces finished consumer goods, would make OVE, PWO, EXO, PT, OFF, SUN, etc.
The BMP would be much more space and construction material expensive (and power if added), say 20 area but only employs 30-40 pioneers. While the FAC would be much more labor intensive, taking up 12 area but employing 80-100 pioneers.
If implemented to the existing universe, the change should be announced a month ahead of time and the FAC building added to the game while the BMP stays as it was. After a month the BMP is changed to match the new building plan and the old recipes removed.
The manufacturing start would be changed to start with a COL, BMP, and FAC. While the constructor still starts with a BMP and PP1.