Vanilla Factions Expanded Classical has large passive coolers that actually reach freezing temperatures.
Medieval Overhaul has Wheat that makes Flour that can then be turned into bread.
As for limiting what can spawn I suggest turning off all factions besides those from Medieval Overhaul and Vanilla Factions Expanded Medieval. And also using the storyteller from Vanilla Factions Expanded Medieval.
18+ Anomalous Base • 8 Year old Anomaly base • Timelapse in comments (media.rimworld.gallery) niemiecki
18+ Rivertown • 8 Year old medieval base • Timelapse in comments (media.rimworld.gallery) niemiecki