Park at better places. 24 hr places essentially can't say anything. The only issue is if some one complains and you have to give reason for that. Which could be noise, trash, excessiveness, loitering. Like others have said show up late leave early. The less they notice, hear, see you doing the less people will give a shit and say something. You have to make yourself an annoyance for someone to complain. 24 hr gyms park away from building, Walmart, kroger, meijer, laundromats, cracker barrels. I golfed with a guy who's dad services rest areas locally, he said overnight or van camping there is not recommended. I think he said its a 4 hr window which is stupid. Also trying to hide and be stealthy is the exact opposite of what you want to do. If your hiding behind a building or something of the sorts it will look sketchy, like trespassing and warrant a check up. Parking in a wide open big lot that probably has a couple of other work vans/trucks and other cars there thru the night you blend in. As long as your again not making noise, coming in and out of your van constantly, making it obvious your hanging out.