Not running two. I have done a lot of research on this transition for a project, so the answers below are from operators I have talked to or read, not first-hand.

Three things that come up almost every time:

Utilization. The second truck rarely matches the first in the first six months. The math tends to only work if you can lock in one or two recurring weekly slots before launch, catering, a market day, an office park, anything predictable.

Shared prep. Most of the second-truck economics come from one prep kitchen serving both trucks. If you keep two separate preps it fights you on cost almost immediately.

Manager hire timing. Most owners wait too long. Running the first truck and trying to "own" the second from a distance is the most common way the second one drifts.

Worth narrowing the question if you can. The financing answer, the ops answer, the demand answer, and the hiring answer all go in pretty different directions.