OK first off the theory that uv maps are supposed to be square and not rectangular is not true. in fact uv maps can be any rectangular shape you want and will work just fine. while some uv mapping programs will only show show maps in a square format that is only their display limitation, but that doesn't really mean that the map in it's final form must be square.

SamTherapy, your concept is sound, and it would be an elegant partial solution to the problem, though of course you still would have to deal with seams (even the bearskin method has seams to deal with) just not as many of them, and while bearskin mapping is certainly going to provide the least amount of seams it is also the method that is prone to the most amount of mesh distortion. the question I have though is that now that there are cheep solutions on the market for true 3D painting for fixing seams, such as 3D Coat, and Blacksmith 3D, is it really so crucial to have those old distorted bearskin maps anymore?