X4.
The smoothbrain OP doesn't know how to articulate his thoughts. Barn door enclosed car haulers exist, but they're usually not large. All large enclosed trailers i've ever seen have a ramp door, because smart people don't want to fuck with separate ramps.
Example:
www.snappertrailers.com
My enclosed has a ramp door, but with the lift, it's too steep to get cars in and out. I used these ramps to extend it, which has worked well for me. You could easily just use these ramps from the ground to the back of a barn door trailer. They make different lengths:
My ramp door is super twisted because it's not built to handle the weight I put on it, but you get the idea: