@Nominal Animal:"Why not do a separate polygon for the warning area?"

Yes! .... thats what i've wanted from the start. But didnt know how to "shrink" or "expand" the complex Polygon .... Matrix scaling looks like what I need?

@Nominal Animal:"You could walk the perimeter to get the safe area polygon first, then visually edit it to add the warning area."

The 8 points around the dog method works just fine as is without any user set-up intervention or knowlage. But If I can simply "shrink" the initial yard boundary down 3 ft by scaling down, I can do away with the 8 points around the dog and the loop iterations go from 9 to 2!

@Nominal Animal:"....you could calculate the distance to the nearest edge or vertex"

Yes ... lets say you measure up,down,left and right for the nearest boundary. That would work fine .... til the dog comes up on a 90 degree inside corner! Here the measuring lines wound miss the "closest boundary" , the 90 degree corner right next to him! The dog would be ZAPPED without warning. The only way around this is to measure not only L,R,U and D ..... but also at 45 degrees from these points ... total of 8 lines! ..... my "8 fixed points" around the dog, and follows the dog, already does this job for me as is.