Aha! I'm so much the same about following rules. Especially trespassing. That and street photography. I would love to do candids but It just is so intrusive and I don't have that desire to talk my way out of things if anyone were to confront me.

When I was a kid though with friends we did a lot of climbing around in construction sites. There used to be vacant lots around my neighborhood and they started building pretty big apartment buildings. Back then there were no fences around the sites and we just walked right in. No one really cared as long as you were quiet and didn't vandalize anything.