I just got back from Whitney and like you I was very confused about the walk in campsites so let me save you some time because I just finished going through it and I can help you not make the same mistakes.
There is a backpacker campground, which is a walk in. and a walk in campground.
despite being much closer to the trailhead than the reserved campsites they are surprising difficult to find. and even more confusing to figure out which is which.
When you drive in you will come UP the road and past right by the portal store. Just beyond that the road will turn around (heading back down) and right into the Day use parking, which seems to always have spaces available. As you pass through that lot you will have the choice to veer left (back to the main road) or stay right which will lead you right into the backpacker campground parking lot. This is a very small lot and there was never a space available there during my entire stay at Whitney Portal so i would not count on it.
However right at the end you will see the signs and the payment boxes for the backpacker campground. The campground is literally just below those signs. The cost os $12 a night and there are plenty of spaces available. Upon finding this I set my tent up in one of the spaces and paid my fee. This was a mistake (for me at least) because I was not yet aware of the second walk in campground.
There is nothing wrong with the backpacker campground except for one major issue. There are no individual bear vaults for these sites. If you camp here you must use the "community" lockers in the parking lot. This means if you are camping there and want to eat you will have to walk down to your locker and pull out your food. It also means you can't really keep an eye (or ear) on your food while camping, or sleeping as it will be at least 20 yards away from you.
It was only after I set my tent up that I discovered the even more difficult to find and MUCH quieter second walk in campground. Once you find the backpacker campground parking lot full (and you will) you will see a sign for "overflow parking" 500 feet ahead. You proceed about 500 feet down the road and make a right into this parking lot. It is actually just right below the same backpacker campground which leads one to believe it is simply overflow for the same campground. At least that is what I thought.
However later I noticed another set of signs on the LOWER side of the overflow parking lot. And below that is the walk in campsites. There are only about 10 of these but I was literally the only person camping in the entire campground. The drawback here is that you have to walk a little further to your site than the backpacker campground,
The advantage though is each site has its own bear locker. Each site has more space. But by far the biggest advantage is even though you are square in the middle of Whitney Portal you might as well be at trail camp because you will have privacy and quiet (other than the sound of the creek).
One more tip. Once you find this campground it turns out it is easier to park further down the road, rather than in the overflow parking as it makes for a flatter, and somewhat shorter walk to your site.
Hope this helps. I really wish someone would have described this better before I got there. Would have saved me setting up camp (and paying) twice.
The walk in campground is $10 a night.
Edited by gmaki (07/18/14 10:39 AM)