For degassing, I mix in the sorbate, metabisulfate, etc., with a stirring rod on a electric drill and stir for several minutes. I then split the batch into two carboys and shake each one side to side until degassed. I cover the mouth of the carboy with a sanitized latex gloved hand. This takes some upper body strength, or develops upper body strength if needed. This ends up being like taking a two liter bottle of soda and shaking until the gas is gone.
Again, a lot of work for this, but I found that it gets the job done.