Would it be possible to introduce some enchantments for temperature control? They could be placed on armor, but it would have three tiers of protection. However, tier three provides the most protection for an armor set.

They should be obtainable as specialized loot from nether fortresses (for enchantments dealing with heat protection) and as specialized loot from igloos (for enchantments dealing with cold protection). However, to provide full protection, your entire armor set would need tier 3 of that provided enchantment, on all pieces.

Applying them to jelled slime or wool armor increases their effectiveness as a whole, for dealing with even worse temperature extremes.