I'd always figured that the magnetosphere was simulated by a Xavier Protocols style set of magnetic field generator satellites (probably solar powered, hardened, armed, and patrolled).
As to Mars' layout, I'd kinda figured that some of the Fen had gone comet fishing in the Kuiper Belt and Oort Cloud and were having fun filming them smashing into the Martian lowlands while giving Mars a decent amount of water down on the planet. So at least a third of its surface covered in water.
As for upping Mars gravity, A.C. CAN manufacture pretty much anything on Prometheus Forge, so Unobtainium isn't too far out of realm of probability. If we need mag field generators as well, we can do that. It might take a bit to create the necessary amounts of the material, but A.C. has been upgrading the Forge's manufacturing capabilities so it'll take less time than you think.
As to Mars' layout, I'd kinda figured that some of the Fen had gone comet fishing in the Kuiper Belt and Oort Cloud and were having fun filming them smashing into the Martian lowlands while giving Mars a decent amount of water down on the planet. So at least a third of its surface covered in water.
As for upping Mars gravity, A.C. CAN manufacture pretty much anything on Prometheus Forge, so Unobtainium isn't too far out of realm of probability. If we need mag field generators as well, we can do that. It might take a bit to create the necessary amounts of the material, but A.C. has been upgrading the Forge's manufacturing capabilities so it'll take less time than you think.