I was in the same predicament in 1996 when my 14 yo son and I did not get a Whitney permit from the east. The ranger suggested Onion Valley start. Wonderful. Have repeated it several times. Being properly acclimatized, Kearsarge is not a big deal. Neither is Forester on the way to Whitney. Just be well acclimatized first. This is important. I have done the route in as little 3 nights (not typical) but most times 4 or 5 , and either as solo or with groups as big as 10. OV to WP is about 50 miles.
The route starting at Cottonwood is another great option. Either way you will face the significant hurdle of getting not only an entry permit to start your trip from the west side, but you will also need an exit permit going east over Trailcrest and down to Whitney Portal
