I got my license in PA and this may have changed since 1989 (boy I'm dating myself) but ours was a pre-determined route on the streets. We always parallel parked on a street in Carlisle that didn't have any parking on it. We had to "simulate" starting in the lane, then backing in on the diagonal and getting within 1 foot of the curb.
My friend who took the same test later that day said there were cones up simulating cars. He nudged one but the tester didn't see it. I was the first that day so maybe they didn't have the cones up yet.
I wouldn't stress about it. For the most part they won't look or act sympathetic, but they are. If you have a large car, just take it slowly and practice first. Inside, they'll understand that you don't have a civic, but outside they won't show any love.
They're more interested in the technique. They want to see you use the back-in method, getting close to the curb without causing monetary damage to any vehicles. Its more of seeing that you can do it and getting a feel for your driving ability than it is actually perfectly executing each task.
You might have more luck taking the test at a more rural location. Not sure where you are in PA, but the smaller towns typically have easier tests with a more laid-back attitude. I took my test in Carlisle, but the Harrisburg test is much more traffic intensive, and parallel parking is much more difficult.
I had such a time with the motorcycle test. I borrowed a friend's bike. I have a cruiser, he has a crotch rocket. That test they give you a painted box on the parking lot and you have to do figure 8s inside it. Not easy on a crotch rocket, especially one you're not familiar with. I just let the tester know what was going on and he let me pass even through I went outside the lines twice.