I've had a look at the problem.
If everything happens more or less according to plan, we should have captured the three current PEACE bases MY 2158.
So if PEACE wants to survive, they'll have to found a new base their MY 2157. The only way possible at the moment seems to be using their Calico colony pod and found a base on (59.43) or so, Yardarm Island. They can most likely defend that base with three units: their scout rover (which we know is on that island - we spotted it MY 2147 or so), a unity rover (I assume they found it in a unity pod while exploring Yardarm Island, as they didn't have that unit a few years back and they didn't build one), and a former.
I've explored a few possibilities, and I think this way we can capture a new base on Yardarm Island fastest: MY 2161:
1> MY 2157 build a cheap impact needlejet in Logic Loop. With hurrying of some four minerals or so, we should have it MY 2158. MY 2160 it can be ready in Thermal Tassagrad to strike at a base on Yardarm Island.
2> MY 2158 (after the Aerospace Complex is completed) we can produce a missile needlejet in Gardens Point. MY 2159 complete, two years to fly to Calico Island, so we can attack MY 2161.
3> MY 2157 send CCS Impaler (filled with one marine - better leave the other behind to deal with the former and crawler) to Lair, MY 2158 to Pamplona. There, before CCS Mammoth leaves for Atlantis, it picks up the amphib impact rover and sets off for Calico Island. It should arrive there MY 2160. So MY 2160 the rover can land on Yardarm Island and possibly even attack a base if it's within two squares of Calico. In any case it should be able to capture the base the year after, MY 2161, I think.
4> If that would not even be sufficient, MY 2160 when we get MMI and drop pods, we can always upgrade some units with drop pods and drop them in or near the PEACE base to capture it quicker.
All this means that PEACE has to found a new base with their Atlantean CP in the next four-five years. The only free land they can reach in that time is Bones Island or the two islands NW of the Atlantic Ocean. If they found a base on one of those islands, we can quickly send CCS Mammoth (which at that time would be in Atlantis ) towards it and capture the base, before they have the chance to build yet another CP and flee somewhere else.
As for changing the impact cruiser destinations, I'd support letting them follow and escort the Mammoth taskforce, but I'm unsure about sending them off on their own in a search towards that transport (which can be in a wide area - hard to find) while there are still 4 ships of PEACE roaming around.
As for the probe skimship: that's even more vulnerable for PEACE attack.
How about sending it west (36.42), and MY 2158 let it attempt to infiltrate the Angels at Coder's Pit?