Guess a wood stove like the bushbuddy would be an option if you want a smokeless fire. I have not tried the stove but am curious if it would be of any use when wildcamping and not wanting to be seen. I had made a burner like it with cans myself but didn't find it that comfortable to use, but it wasn't such a good design as the bushbuddy. But most of the time I have no problem wildcamping with a real fire because people are not expecting anybody to camp out in those small forests..
The kelly kettle is also quite undetectable. I've used it a lot when I lived on a camping and it was not allowed to make a fire there. Sometimes it got noticed though
When travelling the fire in the kettle was never noticed. But it wasn't such a handy format in the cycle bags. I liked it though, because it was possible to put quite a lot of fuel in it.
I know this thread wasn't about stoves.. so ontopic..I have also used the dakota fire in small woodland with many houses in the neighborhood. It's a nice quite smokeless fire, once it's going and the ground has started to dry out. But it takes some time before it reaches that point and can be smokier then other fires if the ground is damp. One trick to avoid this is to line the ground and sides of te firepit with wood or stones.
With any fire you have to be careful not to put on a lot of wood at once. Just add one or two bits of wood at a time, and start with very fine wood and only gradually go to thicker. For smokeless fire I'd say maximum wrist thick wood, unless it's really dry.
In the tipi smoke is best avoided as well.. There we used a small fireplace (size of a small "laxen" woodstove) with square straight sides (as best as possible with stones) to reflect the heat back into the fire. A pipe came out under the fireplace and brought air from outside. Then the tipi itself acts like a chimney if the windflaps are positioned correctly.
So think chimney, air inflow and small dry fuel..