In both views, the wood bar across the top is very important because it helps support the door hinge piece from the weight of the door, and distributes that weight to the top piece and even the opposite piece. Note where the door piece is cut also. you can stain these any colors, this is just so you can see the separate parts and I took the liberty of making the metal "antique brass" for you.
;-)
ok, here is the Pirate chest type hobbit door view.
more conventional hobbit door.
I also put the door knob in the two places so you get an idea of how to go. if at the edge you can go total conventional house (locking) door knob. if you go in the center of the door you would have to use the garage door type chain pull at the latch piece.
(I think I see a hobbit door in one of my future elf builds. :-)
Oh, and with the doors hinged this way, you will once again be able to do the dutch type door, but the heavier the door the more bracing you need and then you are going to start losing the round hobbit shape again to the square door bracing. Oh, Idea 3. LOL brb!
instead of a full dutch door you can go smaller hatch, like the door to the emerald city in the wizard of oz...
lastly, if you cut the door out at a slight angle, say 5-10 degrees, with the "outside" side wider than the inside side, you can get a better seal on the door and any seepage around the sides and bottom would naturally drain to the outside. have the slight rain gutter trim around the top of the door to protect the top half from seepage inward on that slope.
oh, and I just noticed that if you go with the one hinge point, pre-slack the hinge when you measure the holes, so the door doesn't droop from hinge slack when you go to close the door.
With the hatch in the door it is almost a smiley face.
Boy, if you painted that to look like bark on the outside, it would look like you went into a tree!
for the hatched door, I'm thinking you would want a separate, fold-open-and-down-on-the-inside-screen for that opening. That way you could leave it folded down and out of the way, 90% of the time, either hatch closed or handing stuff through, then flip the screen up to block bugs and let air through in the summer. I wonder how that would look with a spider plant on the opened hatch (the opened hatch would be level/horizontal, like a shelf, with the door brace as the support and anchor the other half of the hinge.) I wonder what that would look like with an awning... hmmm...
(speaking of awning, I gotta go work on mine. :-S )