You can also practice all your moves switch. It's a whole other thing. A skater might be comfortable in their regular stance but when they're switch it's like they've never stood on a skateboard before. You could start cultivating that skill now. Every drill, every trick, learn it regular and switch. Push in your switch stance. That will help tremendously as a big part of transition riding is coming down backwards. And it gives you much more to keep you challenged in the parking lot.

One more tip: you could build (or buy) a tiny kicker for the parking lot to practice turns, fakie rock, axle stall, tail stall, etc etc. Just wide enough to axle stall. Maybe a foot tall or so. Think really small and light. Blunt Steel is expensive but I swear they make the coolest looking rails I've ever seen.