I understand now what you were asking for. I would agree that it gives rise to certain problems like the doors. The main issue is that you have many many different vanishing points - like one per square or tile. These are never going to line up and will produce the door issues. Still there is a certain charm to the map. The traditional way to do something kinda like that is to use full isometric view. Usually a 30 degree tilt with infinite vanishing points - i.e. not perspective. You can then take any of the icons and stack them on top of one another and move them around the map without having to adjust for the perspective since its not an issue. The problem with that is usually Z ordering. As in, if you stack some crates up then people behind the crates but on ground level are hidden by the crates. So thats not so trivial to program or set up in a VTT which is normally set up for doing top down stuff.

Well, I think id still suggest using sketchup and texture mapping some decals to your 3D walls and taking screen shots.