I've had very good luck with knocking on doors and asking. I've not yet been refused access to water. Since I sell things for a living I have no fear of rejection. When I find a spot that I
must inspect, I bring the family along. I think they help me seal the deal (especially when we talk to the woman of the household). I guess in a pinch I could hide a netting buddy in the trunk.
I recently had a dream where I could see a great many fish I desire (holy grail stuff) while driving over this small creek. These fish would never exist in the same water but it's a dream after all. I became very excited about the fish I was about to see for he first time and searched for the landowner. To make a long story short I failed to convince the landowner for permission

In my dream I was convinced if my family was with me I could have gained access.