Can you make a 1-way Stargate that can dial out, but not in? I want to build a base that will let people leave, but they have to find their own way TO the base.

The 1-way stargate is close to what I want, but I want the reverse. Is this possible?

2nd request: Can you modifiy the mesh so it's a complete ring, or move the cut part lower? Quite often I set the ring down on a bumpy surface, only to notice that the cut off part of the mesh is floating in the air for all to see. A radial cut, rather than a straight cut along the bottom, would also solve the issue.