Good stuff and thanks for posting.
I know what its like to do that surfing and like you, I try to be careful when I present what I find to others because I don't want others to take my word on something as I am not a lawyer. I figure it out for myself and appreciate when people point things out but it comes down to each of us as individuals being responsible for ourselves and making our decisons with what information if available to us. The best way is to transverse things from the top down just like you pointed out.
The really sucky thing about it here in Missouri is that I have to try to look up local ordinances and wade through all that stuff anytime I feel like OC'ing in a town I don't regularly spend time in enough to know it by heart. Even in some of those towns OC might be allowed but certain places, like city parks, might be off limits and you really have to search through the stuff.
I do most of my OC in Jefferson City and Columbia, as well as in Ashland and when I am fishing at Bagnell Dam. I don't have a CC permit so I have to be a little more cautious about some regs. I know that in Columbia, I can't carry in the city parks. I don't remember off the top of my head if I have to have a permit or not but I remember checking and double checking and knowing that I personally can't do it. I am also unsure as to what all land and streets are considered University property and have to be wary of that. The regulation about the parks wasn't even in their public safety ordinance or related to illegal weapons ordinances, it was in the section about public parks and if I didn't specifically look there, I could have made a big mistake as the day I found it I was taking my little girl to a local park there.
If I want to go to a place like Fulton, Camdenton, Warrensburg or any other place that I might only go to once a year or every few years and I wish to open carry, I may have to do an exhaustive search and I hate it.