I didn't read the whole thread before linking that video, so a few things to consider.

1. There is no federal law stating that sleeping in your is illegal but, some states and or cities do. So if you're in a state or city where it IS ILLEGAL, definitely don't do this lol. They'll just arrest you.
2. If it IS LEGAL where you are, theoretically you don't have to move and can stay as long as you want. But, the cops will escalate things and start looking for other reasons to arrest our fuckery you.
3. Have you considered going to a 24hr gym or something similar? So if anyone hassles you, you're just going to the gym. Just an idea.
4. If your renting a camp site you do have "Campers Rights" and can tell the cops to fuck off. I remember watching a similar video to the one I linked about that specifically. I'll add it later if I can find it. Best of luck though 🖖

i also live in a shitty minivan... getting it over with as quickly and politely as possible is actually your best bet.
one lovely cop expression is "you only need one nail to hang your hat on", meaning: they can pretty much arrest you at any time because there's always some crime or suspicion of a crime they can get you for...
or another way to frame it is: at the end of the day, cops with guns will do what they want... so don't make them want to do anything...
or, more directly, in my decades of vagabond experience... do not try to argue, debate or shame the cops, unless you really want a couple of tickets and several court dates to argue your position...
"i smell burnt marijuana", for example, is a cop's goto for searching your van... ive seen them say it when there was definitely no weed around... but that's not going to help you, until after a bunch of court and bullshit...
...
basically there's no way to make all cops respect your rights without some tedious court shit... you may be legally correct, but that doesn't help until much later...
...
pragmatically, you can try to blend in more... paint rusy spots, etc and make your van look more normy... keep your van clean and free of any character... any self expression...
clear dashboard, clean interior... make it look like you might not be camping in there.
...
another touch i like is leave some folders from the local city college on your dashboard.
there's a huge difference in sympathy between a broke student living in their van, trying to pull up bootstraps or whatever, and what they imagine is some junky/psycho bum living in their van getting free rent.

it's a dumb world but just seeming friendly and sympathetic helps... they don't have the framework to imagine what you're going through...

housey-psychology is all guesswork, but it seems like college, musician/artist, and having a dog helps...

definitely seeming as clean and organized as possible helps... any evidence of beer and you're automatically a scumbag...

reddit sucks, obviously, but the vagabond and vanliving subs have good resources...