DIY insulated hive wraps: Reflectix bubble wrap vs 50 mm EPS foam boards for sub-zero climates

Getting my apiary buttoned down in eastern Ontario. We reliably hit -20°C in January and February with sustained winds across open fields. Last year I wrapped my single hive in black asphalt roofing paper (tar paper) over a layer of double-bubble Reflectix. It survived, but the boxes were quite damp come March. This year I have six hives. I'm debating between building rigid slip-over boxes out of 50 mm extruded polystyrene (XPS, R-10) with taped seams, versus just wrapping them tightly in black corrugated plastic wraps (like Bee Cozy). Does XPS foam trap too much moisture against the wooden box walls, or does the superior R-value prevent internal wall condensation entirely? What is everyone's experience on real temperature buffer?