If I were doing another build for myself I think I would remote mount my blower and run a couple of 2" pipes into the fire box a few inches below the door opening. I would run the pipes in about 4-5" and cut the ends on about a 35-40 degree angle with the long point towards the back of firebox and slightly down to get air flowing back and out to the sides some.
The only thing I am not sure about is how to keep the door from warping. I am not sure if this is the best way but I would like to see.
Here's a couple more pics of the door hinge and latch that mine has. Pretty simple really just heavy angle welded to the door frame on the hinge side with 1/2" bolts and double nuts holding the hinges. the double nuts allow you to adjust the hinge side in or out for best seal.
On the latch side a couple of square u bolts act as catches for the closer tabs. The u bolts adjust in and out for sealing.
The one thing I found out when I built my little ash door(which I'm not using anyway) is not to make the actual door too small. I just made it slightly larger than the door frame and when mounted to the hinges I made it had trouble clearing the edge of the door frame while swinging open or closed. I had to grind a bevel on the door frame and take some material off the edge of the little door.
The ash door you can see in the pic in my other post, these pics are a friends unit but the same door.