Peter,
I think that the freer capturing is really more in line with your
rationale for the edge sqaures in the first place: to keep pieces from
using the edges to hide from Long Leapers.
So how about: A piece may not move to an edge square except to capture a
piece which it could not capture by moving to a non-edge square. This
applies even if the starting square is an edge square. The Swapper's swap
move is a capture for this purpose whether the piece swapped is friendly or
hostile, as is a Chameleon's swap with a Swapper whether friendly or
hostile.