Cut standard door into rear ramp?

I recently acquired a used cargo trailer. It's a home-built unit that is built on an open cargo trailer frame. It's nicely done but only has a rear ramp door, and ideally I'd like to get into the trailer most of the time without dropping the ramp.
So I'm wondering, would it be possible to fit a standard type door into the ramp, rather than cutting one into the side of the trailer? Reason I ask is that the frame rails on the trailer sides are only 14" apart, so that would make for either a very narrow door or a tricky installation. The ramp door by comparison is merely a thick sheet of plywood with a steel frame surrounding it. It could be relatively easy to cut an opening in the plywood, frame it up and insert a door, if I can find or make one in the right size. I'd want the door to be lightweight so the ramp doesn't become a pain to drop & lift.
Has anybody done something like this?
So I'm wondering, would it be possible to fit a standard type door into the ramp, rather than cutting one into the side of the trailer? Reason I ask is that the frame rails on the trailer sides are only 14" apart, so that would make for either a very narrow door or a tricky installation. The ramp door by comparison is merely a thick sheet of plywood with a steel frame surrounding it. It could be relatively easy to cut an opening in the plywood, frame it up and insert a door, if I can find or make one in the right size. I'd want the door to be lightweight so the ramp doesn't become a pain to drop & lift.
Has anybody done something like this?