Lewster (Lew) recommended this to me awhile ago, and I believe he does this on his upgrades.
Consider installing a 50 amp circuit breaker between your batteries and the Airstream. I installed a 50 amp surface mountBlue Sea Systems 285-Series Circuit Breaker
this should protect the Airstream's 12v
systems from any power spikes.
Hopefully, my diagram will not confuse you. Ignore most of it. You can see where mine is, coming off my batteries main power and before it connects to the Airstream's main bus.
And here is a photo of it before it goes to the Airstream distribution bus.