I keep on getting the error message “unable to generate valid starting location gas station in a radius of 3 overmaps”
I’m currently playing the latest experimental
That should just mean that the random gen wanted to place a gas station in that area, but everywhere it wanted to place it was an invalid location for one reason or another (too close to speacial map tiles, other objects in the way, not close enough/ unable to place next to required map tile types like a road etc…)
The game should still be playable without any noticeable effects other than a missing gas station, which shouldn’t be any kind of essential map tile. Just by hitting space or i as it says in the message.
Should only REALLY be a concern if its crashing the game somehow, or if EVERY world comes up with the same issue. 
This has been a problem since the scenario was first added. The rural gas station requires conditions that are difficult to find so sometimes it fails finding them.
With default map settings and no mods active that modify locations (add in or remove / change spawn frequency), for me it failed 2 out of 10 times to generate a start location.
With reduced Size of cities and increased City spacing, it worked fine in all 10 tests.
Setting it the other way around reduced the chance of successful spawning.
So it highly depends on active mods and settings.