Here's the door, inside and out. I've taped on the frame outside at the lowest height it could be without straddling the moulding. The exterior is covered and on a protected side of the house so I don't have to worry too much about weather proofing, but it does get cold.
Our last place had a ladder going up to the bathroom window which I swapped the glass pane for a piece of plywood and cut the catflap in that. A ladder wouldn't really achieve anything in the current place.
Here's the door, inside and out. I've taped on the frame outside at the lowest height it could be without straddling the moulding. The exterior is covered and on a protected side of the house so I don't have to worry too much about weather proofing, but it does get cold.