honestly I've not understood why more offroad type folk have not gone to something like this. Dont know if they make these larger but guess one could put a few on a manifold to accommodate something larger than a jeep hub.
Creeper Breather - Differential Breather Kit Prevents dirt, debris and water from getting in to your axle through the stock axle housing breather. Expands and contracts to accommodate increase or decrease in housing pressure. Kit includes one housing fit
trail-gear.com
Or even a tank that works like a radiator overflow bottle but with air. Or a closed overflow bottle *system where you put a little vacuum on it at install giving room for things to pressurize into it when needed then drop back to slight vacuum state when not hot and working.
*not sure I like the closed system. if a leak is in it when in water the vacuum might suck water in. Granted once it sucks in enough air to equalize instead of being at vacuum..... then the system is negated but at least it is not "sucking "water in
