Best as I can remember… But maybe I am conflating two stories together?
Aliens sent many men to a more primitive earth-like planet/reality to survive and thrive. The aliens did not choose their transportees with care. They got some defective personalities that were more interested in being a despot ruler and inflicting cruelty on the natives than creating a micro-culture where everyone thrived. The participants got to choose some modern supplies to take back with them.
My memory says that the protagonist was a 'good guy' and wanted the best life for those 'natives' he influenced.
Our MC had people within his influence build a long wood wall to surround the town and a nearby field keep out the large predators that roamed the land. HUGE bears maybe? The wall had gates.
There was a dormitory style housing structure.
He put an electric windmill on top of a tall wooden tower.
His 'people' dug a large sewer down the middle of the street to empty into the nearby river.
There was a coup while the MC was out of the town/compound and he crawled up the sewer to get inside the walls and re-take control. IIRC, the dormitory burned. There were many casualties.
Here's where I may be conflating stories…
I remember he then gathered the survivors and moved en masse south toward a warmer region. They had some 'incidents' during the trek. They finally settled on an old alluvial plain above a river.
And that's what I can remember.
Does any of this trigger your memories of reading a story with these elements?
TIA