Yeah I was planning on doing the same thing with the door cards if you had good vinyl for sale. I've seen those mdf ones fall apart after a couple months, it is not even close to the right material for a vehicle especially a door as no matter how good your rubbers are moisture still gets in. Take your original panel if it has a good enough shape to a plastics place and get them to machine a new one from abs, it takes to the adhesives for your vinyl better too. Shouldn't cost much.