I think the only rule we have is: don't be an ass. We discourage the stupid driving in/out of the parking lot, especially after another member unintentionally hopped a curb, missed a pedestrian, and hit the bus stop seat the pedestrian was sitting on.
Several of the guys on the LX side own trucks and will bring them on occasion, so it's not unheard of to see 2-3 trucks there, just follow the common sense rules when parking, back in, and separate the trucks from the cars, who wants to associate with those car 'riff-raff' anyway.
Dave, Linda lets you drive her truck during the week? That's nice of her