The good news is that your son has earned your evaluation that he is "level headed". The bad news is that, even so, it is only "for his age". Unfortunately, the norm for his age is that he sees himself as "ten feet tall and bulletproof". Thus the feeling that, without ever having done it before, he and his friend can drive through the night. The statistics on such endeavors are chilling. I will tell you from personal experience that I tried a similar trip for Spring Break while I was in college. We were lucky and only got pulled over by the North Carolina State Police for weaving from lane to lane at three in the morning and 'escorted' to an all night truck stop for coffee and a rest. I'd almost make this a test of his maturity and readiness for such a trip. If he really insists that he and his friend can drive through the night, then he's not ready for the trip. He has to be willing to bend to reality, be it his own limited humanity or any vagaries of the weather he might encounter.
AZBuck