Yes, they will allow members to visit the resort. There is a gate and if there is sufficient parking when you arrive I'm sure they would welcome a visit.
As for seeing a villa, as long as there is a villa unoccupied and already cleaned, they are usually very generous about allowing a tour. You might even want to call ahead - since it's quite a committment from Charleston.
In the past, the front desk has not been as generous about allowing visiitors to go to the Beach House, as that area is accessed by permit and also by room key and is available only to guests registered at the resort.
Enjoy!
