In my outdoor session I try and travel as light as possible, using a pack-sack with the most important gear i would need to paint on site. One of the most important equipment is an easel. Although there are many easels to choose from, I have opted to use a camera tripod together with an aluminum plate which screws on to a drawing or painting board which will also connect to the tripod head instead of the camera.
I have found this method of setting up my easel the most effective and convenient way. First simply because my easel is light and mounts to a good size and secondly, the bracket is quite stable which and enables you to turn and guide you watercolour flow in any angle using the tripod leveling features.
This aluminum plate is available on line from Ken Bromley at: Ken Bromley tripod mount bracket