Do they have semi truck parking over night

Yes

Yes, they have plenty of lines marked on the lot to fit lots of semis on it! As well as campers! This is one of the best WM's to allow semis to park!

There are semi's parked there on the lot but there's not an official parking lot there for overnight parking

Would be best to ask a manager. Some do not allow it. It all depends on location and local laws.

I did see a couple of truck by me when I spent the night in my motorhome. I believe I saw a sign, no trucks. But I would ask if it was ok

Some Semi trucks do park there overnight

No