You can't win. When it comes to stealth, you can't have a system that is simple, realistic, clear and complete.
* Simple systems are going to be brief - and brevity is the enemy of complete, clear and simple rule sets. They'll leave too many questions uncovered to be clear.
* Realism in all situations can only be achieved through a large volume of rules. That is going to be complex, hard to delve through.
* Clear rules are rules that are easily managed, remembered and utilized. If a situation is complex and subject to a lot of conditions, it can't be clear.
* Complete rules need to cover any given situation that might arise. There are so many situations in D&D where stealth might be desirable that covering it all explicitly would require volumes of complex rules with countless exceptions.
To me, this edition gets it right: It gives us a very basic mechanic and tells the player to ask the DM if they can try stealth in a given situation. It makes it a judgment call and tells you who the judge is. Players might not love the judgment, but at least the rules are clear on how it is to be made. That is the best solution - even if it is unsatisfying.