It should be fine most of the time in the NE at night.
I would skip Death Valley on the trek.
Seriously, it can get hot in the SW a lot. At 110 F it may hold 90. Even here in southern Missouri or northern Arkansas and anywhere south of here it can overwhelm a single unit at times.
I would talk to a dealer or FR on the viability/ease of an upgrade. It might be a piece of cake. I really didn't know dealers order them without at least the 50 amp service and pre-wired. Many dealers just get them with the 2nd AC but mine just has them all pre-wired.