Do you think they could be written down and applied for 5E?
Funnily, the D&D Next Stealth rules were more clear than 5E final version
Stealth
When a creature tries to hide, it relies on its
Dexterity to remain unnoticed. A creature can
attempt a Dexterity check to sneak around,
moving quietly and using cover and heavily
obscured areas to avoid detection.
There are two ways you can hide. If a creature
can’t possibly see you, you need only to avoid
making noise to avoid detection. If a creature
might see you, you need to keep behind cover or
stay in heavily obscured areas to remain hidden.
When you try to hide from one or more
creatures, your Dexterity check is contested by
the Wisdom check of any creature who might
notice you or the Intelligence check of a creature
that is actively searching for signs of your
presence. You make one Dexterity check for this
contest. Note your result, and use it as your
check for all contests until you are discovered or
stop hiding.
Conditions for Stealth
In order to avoid detection, you need some way
to remain out of sight—either something to hide
behind, or an area of poor visibility to locate
yourself in.
Stay out of sight. You can’t just stand in the
middle of an empty, lit room and hope to avoid
notice. Something must conceal you, perhaps a
large object, a piece of terrain, or an immobile
creature of a sufficient size, such as a slumbering
dragon. Regardless of what stands between you
and a viewer, it must cover at least half your
body for you to hide behind it.
An environmental phenomenon that obscures
you from view can also provide a means to hide.
A heavily obscured area typically contains
darkness, opaque fog, or dense foliage. A
creature in a heavily obscured area is out of sight,
just as it if were hiding behind an obstruction,
and thus can try to hide. A lightly obscured area
typically contains dim light, patchy fog, or
moderate foliage. Some monsters and characters
have special abilities that enable them to try to
hide even in areas that are only lightly obscured.
Stay quiet. It’s assumed that you try to avoid
making noise while hiding, and your Dexterity
check also represents your ability to keep quiet.
If you make a noise, such as yelling a warning to
an ally or knocking over a vase, you give away
your position and are thus no longer hidden.
Benefits of Being Hidden
When your enemies don’t know where you are,
you can take advantage of the following benefits
You cannot be targeted by a creature from
which you are hidden if it uses an attack or a
spell effect that requires it to pick a specific
target. You can still be affected by area effects.
You have advantage on the attack roll when
you attack a creature from which you are hidden.
Making an attack usually reveals your position.