Do they have big rig parking?

Looking at Wal-Mart it will be on your left hand side in the back. You will see the other rigs and can't miss it

In the back of parking lot I've seen rigs park. No security there to tell you to leave

It is not authorize by Wal-Mart but they will not ask you to move. There is no security. You park at your own risk at the back. Lots of persons do take advantage of it and park there.

I don't think so. Try calling the store.