If you end up getting the escape door but your car door doesn’t clear you can build ramps the car sits on in the trailer to raise its height to clear, that’s what we did to our trailer at work we used to deliver vipers
The only thing I didn't like about that is that it would make a trailer awkward to use as a cargo trailer depending on what you're trying to load. I also used to sleep in the trailer and questioned the wisdom of 2x12s screwed to the floor when I walk into the dark trailer drunk at midnight. Aside from that it's an good, simple, cheap idea.