Is this parking lot viable for overnight parking & sleeping in vehicle?

No

IMHO, as far as safety it is. Really open lot. I can't comment on their security but I think it is otherwise safe.

No sir Mr. Isom , and yes they do have security that patrols the lots.

I am not sure, as I've seen the tractor trailers parked there before. Individual vehicles I don't know. I am certain that they have patrol in the parking lot!