One additional Idea:
Instead of showing all PX bases with the second PX research (forget its name, bit I’m sure you know it 
), you get revealed only one base (Edit: of course close to the starting base), that contains one Manticore and maybe also one Scarab, probably both somewhat broken so that you have to spend resources to get them up. This can be combined with an additional mission on the ground to take the access lift or something similar to the Pirate King mission in the base, probably here you can overtake the scarab.
So many possibilities … 
Edit:
This second base then can reveal all other bases.