This is an ex-pen but wondered if something like this would work. I used an ex-pen across our hall entry for sometime, until just recently getting a pet gate to go across our front door, in between the storm door and wood front door.
I realize you couldn't pressure mount this pen, but when we used the ex-pen it wasn't necessary, none of my kids could move it, to get around it (or they didn't try
). Plus, you then have an ex-pen also if you want to take it outside.
Walmart.com: IRIS 4 Panel Indoor/Outdoor Plastic Pen White: Dogs