We were at FW with our M/H 3 weeks ago. While there, we took the M/H to Camping World to have a new awning installed. The day we went to Camping World was in the middle of the time we had our campsite reserved. There was no problem leaving the campsite empty while we were gone. We did let them know when we checked in, that we would be gone for several hours that day.
When you leave, go out the gated exit into the main parking to FW. Keep your room card with you to get back in. You can either come back in through the gated entrance and swipe your card or through the drive-thru check-in area and just show them your card.
Enjoy FW!
Poohstyx