We considered just putting it up, but it would be in the driveway, so very visible from a somewhat busy intersection and street. Looked at the potential fines and didn't want to risk it. I googled similar stories and some people who put something like this up in their backyard have been able to get away with it.. the main danger, as others commenting said, basically seems to be nosy neighbours that will tell on you.. but something so visible, we wanted to do it properly, so this wouldn't be hanging over our heads for years and years.
Yeah, heading down there is something we considered as well, but figured sending them an email would be a good start. I already spoke to somebody over there on the phone, but it's possible they were in the wrong about how this should technically & legally go down? So we'll see. If we don't hear back or if there's issues, we will head down there, it's often easier to communicate in person and get the feel of the situation.
Luckily we get along great with the immediate neighbours, and there's somebody across the street who has a really ugly and flimsy tent-like structure up. Nobody seems to care, as far as I know anyway. I suppose they might have had to get a permit for it too, but maybe they didn't? Either way it seems to me that what we want to put up looks a lot nicer and is a lot more stable.
There are also no HOAs anywhere near here, I can't imaging living in a house that's got a HOA attached to it. Seems like a nightmare. Thankfully they don't seem to be that common here.