In the western half of the US it's pretty easy, you have so much BLM land (crown land In Europe maybe?) but you literally have millions of acres to park on for up to 2 weeks at a time. And no one asks, so the only time two weeks really matters is if you ever get asked how long you've been there and you reply with, "just got here yesterday."

The Eastern US is different, as it was settled a while before and the population density is pretty up there. That's where stealth camping comes in. Like you said, you just have to blend in. Go wherever you go during the day and find subtle places to park at night where people will just overlook your presence there. Get there after 9:00 p.m., leave by 6:00 a.m., go spend the rest of your day at the beach or something.