Do you have a stacker for your downrigger? Any lead core?
If I only had one downrigger, and no other way to get a line down deep I would just go bass fishing. I might jig over some over the deeper holes in the lake and hope for a cold water fish, but I don’t think I would troll. Bass fishing is way to good there.
That being said I would run your rigger as deep as you dare, and put a DB smelt, or Top Gun spoon out behind it at 2+\-mph, if I was set on trolling. Concentrate on hiding from the sun early, and fishing the deep sections of water in that area. Then go to the deepest section of the lake once the sun comes up and do the same thing.
If you are by yourself and only have the downrigger to get down deep I’d also run a line in the prop wash, and catch some bass to keep me occupied. If you don’t have a release for the DR that can be set very lightly be sure to check for those mini smallmouth, that seem to lurk at the lower depths, often.
It’s a really awesome lake to be on this time of year. Beautiful setting, but the trout/salmon don’t come easy there.