be the first rider in the group. wala! your dust problems will be a thing of the past! haha.
thats the thing i hate about riding with my brother or wife, im so much faster id leave them behind in a second if i was in front. so i get stuck in the back eating dust sandwich all day and have to clean my air filter after one weekend of riding!
You should just do what I do... Ride the front at your own pace and when you get to a turn that you want to make or quite a distance in front turn around and run back to the slower riders until you see their headlamps then turn around again and ride back. This way you can ride at your pace and you get to cover twice the miles and have twice the fun plus no dust. With a bike it's easy to make the flip flops quickly.