Look at bus connections back to CM right from Lone Pine: to Yosemite is easy, CREST to Yarts, then Greyhound or AMTrak (yes a lot of AmTrak routes include buses) to Visalia, then SEKI shuttle. Requires a very early am start in Lone Pine (CREST stop is a block or two from the Hostel) and possibly an overnight in Yosemite (Camp IV or backpackers CG with a next day permit). I would look into whether you can get all the way to Visalia Holiday Inn in one day, then catch the SEKI shuttle in the morning.
Great lollipop route would be return from Whitney by Pants Pass or Pyra_Queen Col. In fact from Whitney summit, that would probably be as fast as by bus from Lone Pine! See Steve C's HST report from last year, and keep in mind that both Pants and PQ are easier E to W.
BTW, at Whitney summit, you HAVE done the whole HST. Like the JMT, Whitney is the terminus, not the Portal.
