Any diesel 1998 or newer require smog certificate.
Coming out of state, or local doesn't matter.
BUT ,, there are lot of exemptions.
Vehicles with more than 14K gross are consider commercial and they don't require smog, while they fall under 20 years engine replacement rule.
Than RV seems to be exempt to almost everything.
I would call CA DMV and they have convenient call back feature, so you don't need to hold for 1 hr.
Worse come to worse, you will have to get smog certificate, what is strictly formal in CA. No probe, no rolling, no engine reving. They plug OBD (if equipped) to check for codes and make sure the EGR and CATs are still there.
Actually dealing with rare vehicle, they will open the engine compartment, try to make smart face and close it, letting you go in 2 minutes.
They did that on my Mercedes diesel sedan.