We have a new to us, Georgetown motorhome. It has a middle entrance door.We have always had the door up front by the passenger seat. In the other motorhomes, there was an automatic step cover to cove...
I can't think of anything except making your own with some wood covered with carpet. Meanwhile I would probably get a big bean bag and stick it in the hole when everyone was in for the night, at least if anyone falls in, it will be a soft landing. I bet the dealer could help you out with some ideas. Good luck.