Oh, yes, I do this. Shampoo just at the scalp, conditioner everywhere else, and I just used up the last of my old stock of shampoo bought on sale, so except for dandruff shampoo everything is SLS-free. And I can just rinse-and-condition a lot of the time after a ride, but it still dries it out a bit. I really, really hate the smell of vinegar, so I'm not willing to go to vinegar instead of shampoo, which would probably be the next step.
Another advocate for the low bun here, it doesn't get in the way of my helmet, and I also wear a bandana which helps to hold everything in place. My hair is waist-length and curly, and if I don't tie it back like this it ends up in one big tangled mess!
I also only shampoo the scalp once a week (when you rinse it washes the ends anyway), otherwise I just rinse with water to get the sweat out, then apply conditioner, but only from the shoulders down.