My advice would be to stay off of any private property unless you have WRITTEN permission. Yes, it can be difficult to get such permissions, but if you do not, you risk having a not-too-pleasant chat with law enforcement. And I emphasize written, because on a Sunday morning, there may not be any of the property owners available to corroborate your claim of permission.
The park sounds like a much better choice. As does any location that is open to the public.
However, no matter how much you may be in the right regarding your choice of location, it is nearly inevitable that at some point you will be visited by the cops. Mr. & Mrs. America are so primed by the media to be paranoid, that some dolt will see you and get their undies in a bunch worrying.
A few years ago, I was sitting in the parking lot of a city park along the CN tracks in north-central Wisconsin, in the middle of the day, with my tripod set up with the camera mounted on it, when this local Barney Fife rolls up and asks me (seriously) what I was doing, why I was there, why was I taking pictures of trains, etc. Never mind that I was in a location totally accessible to the public, that I am a average-looking typical white male of 60+ years old, and that my little Ford Ranger pickup was bright red. This “peace” officer (do they still call themselves that?) started questioning me. He was a real piece of ****, and if he was really that stupid, he did not deserve his badge.
But, and this is my point, he has the authority, and there is nothing you can do about it except be polite, truthful, and hope for the best. Certainly there are smart, reasonable cops; but I got tired of worrying that I might get the cop who just got yelled at by his boss, or his wife, or that his donuts were stale. Getting hassled is one of the main reasons I gave up railfanning; it just wasn’t worth the risk.
I sure liked it better when we lived in the land of the free.