Let's cut the number of entries from the Portal to ten a day. Day hike or overnight. If you want to see Whitney, you start from farther away or you're one of the super lucky ten. Onion Valley to Whitney is still a doable day hike for some.
Let's cut it back until all the current poop is broken down in 10-15 years. Or whatever. Meanwhile, we can educate people on the evil of poop and once the area is restored some, loosen the quotas up.
To make it fair, once you have gotten your magic permit for a portal entry, you can never get another one and have to use another trailhead.
If people can't mind their poop, we will have to restrict access to limit the shit.................................DUG