How do I spawn in an actor with another actor attached to it?

I have a tram actor, and I want to attach a door actor to it that opens by moving along a spline that is attached to the tram (the tram blueprint contains a reference to the door). Making this work just by putting everything into the level is easy, but is there a way to make this an equivalent of a unity prefab so I can spawn another tram with an attached door actor with its reference already set?

Create a BP (actor) and add the components together. Then spawn that actor.

Or Spawn X Actor and have the Begin Play of said actor spawn the other.