From my perspective (trail/road runner) I agree with <Audiograce>. During the week prior to an epic effort or race, you can only maintain your fitness level or get injured. The first rule of thumb is to maintain the normal workout intensity until 3 days before the event, but with extra rest. Second rule is to "go with what got you there". In other words, don't stray from your normal pre-workout routine.
In case it will assist you, below is my plan for the week prior to my Aug-17 Whitney round-trip run (my annual birthday run). During the high-intensity trail training runs, I try to visualize sections of the Whitney trail while maintaining the approximate Whitney-level discomfort.
Aug-09: 18mi difficult trail run
Aug-10: 8mi social trail run
(pm) upper body weights (skip 2nd run)
Aug-11: 9mi [HARD] hill intervals
(pm) upper body weights (skip 2nd run)
Aug-12: 2x 30min Stairmaster
(pm) upper body weights
Aug-13: 11mi [HARD] uphill trail tempo
(pm) upper body weights (skip 2nd run)
Aug-14: 2x 30min Stairmaster
(pm) upper body weights
Aug-15: Drive (7hr) to Lone Pine via Yosemite
Social 6mi trail run with wife
Aug-16: (am) 90min [LIGHT] Cottonwood Lakes
(super-saturate carbos)
(pm) (super-saturate)
Aug-17 (am) (Super-saturate, super-hydrate)
Whitney round-trip run
Hope this helps!
Good luck.
--Adam