You may be able to secure a spot at a welcome center or rest area but that late at night might be full (but not necessarily).
We usually stop in Santee State Park (was $16 on weekday and $21? on weekend) in SC and a short drive from route 95...a place to summarize if necessary.
Walmart are not tops on my list...stayed in a Cracker Barrel in Amarillo in the fall and have decided that that is not tops either especially since they are in pretty populated areas (thus noise).
Welcome to VA is our first stop usually.
Boondockers welcome is another option.
Worth it if you will you use it.The rest area south of Jax fl has separate rv area...always nice. Casino Miccosukee as well in southern florida if you go to Keys.