Option 2 has been done in the H&K P7, but my guess is will be tricky to keep the dimensions similar.
The P7 setup, including the gas port does seem like the way to go about it.
As I understand the P7 got hot at the port area but that looks like it was because the gas had nowhere to go directly except back out the same port. With an intake port and exhaust port, it might work for a 9mm Parabellum without building up too much heat. \
Such a change would explain a full suspension of manufacturing during the reengineering process.