Well, I would head up to Merced Lake very early the first morning, bypassing all this:
http://www.highsierratopix.com/communit ... =1&t=12600The Meadow Fire was awful. Camping in burned out areas, under dead standing burnt trees, is dangerous.
I'd go up the trail toward Florence, Bernice and Gallison. I'd visit Vogelsang Peak on the way over the pass to the HS camp. I'd have a dinner at the camp that I reserved in advance (they don't take walk ins) and spend a layover day exploring as far down as Lyell Canyon with a day pack, and come back for another night. Then I would come around the loop to Emeric and back down into the Merced Lake area, then climb out of Echo to take the higher trail over to Moraine Dome. I'd camp somewhere around there, perhaps on the dome itself (I have carried enough water before to dry camp in high places), and move on to Clouds Rest. If the campsites around Sunset Creek are also burnt out I'd just hike out at that point, using a headlamp if necessary. Or, since it's the last day out and my bear can is at its lightest, I would instead go over to visit my favorite place in the Valley, the Diving Board - it doesn't have an official trail to it and you have to do some class 2-3 to get to it, but there is a campsite up there and it would be worth it to me to carry plenty of water up that steep hill. I'd have the best view of the valley floor and the area all to myself. Personally, I have no desire to re-experience Half Dome with its line of ultra-rude people - getting stuck behind a panicked person and in front of an angry cable-shaking jerk with no empathy for scared people is just not the wilderness experience I desire.
If I came out early I'd take advantage of the night after a trip to stay in the backpacker's camp, and the following day day hike up to Upper Yosemite Falls.
Of course, you can go to Half Dome and then out to Happy Isles as you plan to. Not sure about the status of Little Yosemite campsites, but I am guessing they are okay since they opened that area for camping. I have no desire to stay there again, myself.
Good luck.