Preparing for a long hike

I'm signed up to do the Suffern-Bear Mountain End-to-End hike with the Appalachian Mountain Club in a week and a half. This annual hike travels from Suffern at the southern end of Harriman State Park to Bear Mountain at the northern end. Over 24 miles hikers gain 6,000 feet of elevation, making it a challenging day hike.

I've been training for it for a while, but I still don't know if I'm ready. It will be the hardest hike I've ever done - beating out any of my Nashville Hiking Meetup Death Marches. I took a look back to see how it compared with my previous excursions:

Most elevation gain in a day:
11th & 10th place: South Mac/Chimney Top (Frozen Head, TN) - 3720 feet over 10.3 miles and Hunter Mountain (Catskills, NY) - 3720 feet over 4.5 miles one-way
9th place: West Kill (Catskills, NY) - 3762 feet over 4.5 miles one-way
8th & 7th place: Rainbow Falls (Smokies, TN) - 4000 feet over 6.5 miles one-way and Mailbox Peak (WA) 4000 feet over 3.75 miles one-way
6th place: Twin & Indian Head (Catskills, NY) - 4000 feet over 3.1 miles one-way
5th place: Sewanee Perimeter (TN) - 4124 feet over 20.6 miles
4th place: Failed attempt to summit Mt. St. Helens (WA) - 4200 feet over 4.5 miles one-way
3rd place: Ramapo Torne/Russian Bear (Harriman, NY) - 4344 feet over 9.92 miles
2nd place: Mount Saint Helens (WA) - 4500 feet over 5 miles one-way
1st place: North Bird Loop (Frozen Head, TN) - 5500 feet over 15 miles

Longest dayhike:
3rd place: North Rim-Plateau Loop (TN) - 17.9 miles
2nd place: Sewanee Perimeter (TN) - 20.6 miles
1st place: Palisades (NY-NJ) - 21 miles

The only hike that appears on both lists is the Sewanee Perimeter trail. While shorter than the SBM, it's not markedly shorter. It's also similar in that it's a series of ups and downs, rather than a steady climb up a mountain. Similarly, the North Bird Loop hike had almost the same elevation gain as the SBM, and it was arguably harder for being shorter and thus steeper. Of course, none of this takes into account my relative fitness at the time.

But, hey, at least I'm not trying this hike.