Sadly, somewhere along my playthrough something adjusted mech raids to be 100% after a certain point. I could not put my finger on the cause so I had to remove the mechanoid faction as a whole to be able to get regular raids. I made a rule for myself, 1 year of mining on a nearby mountainous tile was allowed by the local population.
After that we were on our own. We got as much steel as we could to build the intitial base. By growing rice, cotton and healroot we got our own production going. We had a psychopath butcher the raiders, for making chemfuel and clothes to sell. There are unlimited traders here, although not for free. Making all the armor was a lot of tedious work, we had to learn a lot the hard way. But most of us survived and we are now one our way to an unknown destination