I still think using Passive Perception and Stealth skills as a basic tool would work. Passive Perception of 13 means that a Stealth roll is not necessary until your character gets to within 13 feet, if sneaking up from behind. If from the side, double the range. Stealth check at 26 feet away. Front arc? Line of sight using lighting and terrain.
So, you are sneaking into Blighted Village via the east gate. Stealth check as soon as you pass through the gate because you are in line of sight front arc. Coming from the south, you take out the goblins at the south gate and sneak up on the goblins on the roof of the apothecary. You are in their rear arc. No roll is necessary until you get within like 9 feet - I think their Passive Perception is 9.
One roll is all that's needed per character per arc except Front arc. None of this having to roll every 6 seconds stuff because of the mechanics where some are yanked into battle while some are not. Front arc is the exception where you still roll every 6 seconds.
Then, if Stealth is successful, it's like invisibility. If you attack, you roll again. Period. No matter the arc. Make Stealth an Action except for Rogue Cunning Action and viola. Stealth fixed.
