I wanted to tell you, I went to Lost Lake last weekend on the northwest flank of Mt. Hood during the new moon and got some good pictures of the Milky Way and the mountain in the water from there. It's a lot like Trillium lake, only if you come in from the south or southeast, you'll be spending about an hour on one lane national forest roads, and about 5 miles on gravel. I got there from Zigzag, turning onto Lolo pass road. A buddy and I camped at McNeil campground on the west flank of Mt. Hood which is 8 miles as the crow flies from Lost Lake, but it took us about an hour to drive there, and I was seriously carving some corners.
The other option is to come in from Hood River...but if you're coming in from the south that adds about an hour on to the trip, so it's 6 to one, half dozen to the other, but its all paved, and from what I understand, two lane roads.
You can actually camp at Lost Lake, but you need to reserve a spot ahead of time, that campground fills up quick.