Do this store allow Overnight Truck-trailer parking?

Yes just let mgmt know and your all good

Not all Walmart's let you park for even one night. This is per management at more than one Walmart.

Yep

Yes it allows overnight parking for trucks, trailers and RV's

We stayed in their parking lot, at the furthest end. On our trip across 4 states, we stayed in several walmart parking lots, they never gave us any trouble for it but we never stayed for more than one night.