For maps I like
Tom Harrison maps (.com) of:
MT WHITNEY HIGH COUNTRY TRAIL MAP start at top and exit at bottom.
Needs one more inch to the north
TRAIL MAP OF THE KINGS CANYON HIGH COUNTRY gives you that inch you are missing
Tom's maps give you mileage that is close enough OR I use a .09mm Pentil pen (or equivalent) and lay it on the map. Its about a day's travel (10 miles +-)
Onion Valley start and suggested overnight locations: (all had bear boxes - check recent)
Kearsarge Lakes (altitude acclimatization check in the morning - you can still bail if a problem)
Upper Vidette Meadows
Over Forester at 13,200' best be fresh for this
Tyndall Creek (you could return here from Whitney and exit over Shepherd Pass to Onion Valley)
Guitar Lake (or above it)
Whitney (you could exit here if you use your HST from Crescent Meadow permit)
Guitar Lake
up Rock Creek
Solder Lakes (Mitre) 3.5 miles up Rock creek
Over Army Pass
Cottonwood Lakes ( you could push to Horseshoe Meadows. it will be a big day)
Horseshoe Meadows (and car)
7/8 nights. (6/7) if exit over Shepherd Pass)
If you push it to Vidette Meadows first day, then Tyndall Creek, two nights at Guitar and return to Tyndall then over Shepherd it is 6 very hard days.
High Sierra Trail (from Crescent Meadows on Tom's Mt Whitney High Country Map.)
Bearpaw Meadow (long first day 14 miles)
9 Lakes Basin or top of Arroyo (killer two days) (better if 3 days with stop at Hamilton Lake)
Upper Funston Meadow (hard day down hill miss Moraine Lake)
Junction Meadows or top of Wallace Creek
Above Guitar Lake
Whitney Summit
Some where down the hill for the last over night
out to Portal
6 hard nights (Better if 8 nights - lots of food weight)
Both trips are all on trails.