If nobody knows that I'm there, none of this really matters.
IME, if you stealth camp so well, that nobody ever knew you were there, any ranger worth their salt, would allow you to continue. And might even enjoy your company.
Uhhmm... any ranger worth their salt driving along, finding you dispersed camping on roads not so marked, national forests I mean, is gonna tell you so, not continue. If a ranger sees you to "allow you to continue", by definition he knows you were there and you've failed your stealth check.
@LoganTX86 there are tons of resources on where you can camp. Every state has a website detailing their state lands and parks, and how you can camp there. Every park has a site and phone # to get info. BLM has a website with camping restrictions. U.s national forests has a big website with camping info, then each forest has a Motor vehicle Use Map showing where you can drive, camp, and dispersed camp up to 300ft away from roads. You can stop into USFS offices for each forest and chat with rangers about where is good too, they have always had a paper copy of the MVUM showing roads and allowed camping to physically grab too. I have probably one from every Nat Forest in AZ and NM in my truck now.
You can use other camping sites that show dispersed and primitive spots, I like ioverlander.com as a good 1st look.
You can watch various YouTube channels on overlandlanding, many go through their methodology for finding places. Donald at SoftroadingTheWest has a video about 8 months ago showing exactly your question, how to find spots.
It is a knowledge journey that relies on you sitting down and doing research, 1st is look at websites of where you want to go.