in regards to Opti's original post about tester walls...
if I'm getting the concept right (I feel pretty comfortable understanding the concept), then an artificial island hole, say with haybales, logs, RR ties, etc... would have a tester wall border if you were playing it "standard" without the artificial island rules.
The thought is that most island holes have a low defining border that stops skips, and are often at a distance from the pin to qualify as an Opti tester putt.
So...in concept... you could have a short tee that plays log encircled island as an island hole, and a long tee that plays with the logs as a tester wall (no artifical OB)?