We will be shopping at your location to stock up for our 2 week vacation in a travel trailer. Will we be allowed to park it overnight-for a few nights until we can leave this weekend?

You would have to ask the store. I know some Walmart stores do allow this, but I would ask just to be sure. They usually have designated spaces.

It would be safe to check with store management. I have seen trucks and other vehicles parked overnight there many times.

I'm not sure but the police do patrol alot. I have seen 18 wheelers parked overnight. I don't think it should be a problem. You should call the store directly.