Greg, things to think about:

Be sure plane is a high wing one. Seems the Cessna 171 is used often, and these are high wing.

Use a moderate telephoto. I might be inclined to go with your 75-300. Pilot can generally only drop to 500 feet, I believe, so you should be OK with this. Gives you a little leeway to be able to shoot from further away and crop down if need be. The pilot can also fly higher if you need to get more image into your viewfinder.

With that said, shoot at higher resolution so you can crop down and still have a good image.

Use a BIG and FAST memory card. If you have a spare, put it in your shirt pocket, not your pants pocket. The fast card lets you set your camera to "auto rip" and burn off a series of pictures as you fly over or past a light.

While you want to compose your pictures, I am a believer that shooting a burst of images will help offset the potential for a wing dip or catching the wheel in one image. Thus the "auto rip". Sometimes the best approach is to just put the camera out the window, point it towards the light and trust autofocus.... you'd be surpprised at how well some of the pictures will turn out. Do be sure the camera is securely tethered to you if you stick it out the window.

It should go without saying to be sure your battery is fully charged. With the battery life DSLRs enjoy today, it can be easy to forget to charge the battery. Do charge it the night before your flight.

While in some planes you might be able to change lenses, don't plan on being able to do so. When you get to the airport be ready to get out of the car, go over details with the pilot, and have your camera ready to go. You should have your pilot show you the route he plans to fly, even if you have previously discussed it with them. Make a pit stop before you get in the plane..... Do ask the pilot whether or not they think you might need a jacket or sweatshirt on, and how long they are projecting the flight to be. You will get into a routine after your first light or two and will do fine. As you travel from light to light, check to see how you are doing on card capacity - change them out if you need to, but do be careful. Personally, I don't waste time trying to review images I have taken other than to take a quick look to be sure I was successful. I like to enjoy the flight and the view you should have.

Have fun!