The only alternative I know of is to drive the car to Onion Valley and then just one hitch-hike back there after the end of the hike. Hitching is always easy from the Portal down to Lone Pine. I don't know about the section to Independence or to Onion Valley. There is a shuttle bus that runs from Lone Pine through Independence, so if you drove your gear up to Onion Valley, then parked back at Independence, and tried hitching up to OV, that might work.