Before the mast step was moved aft I tried all the suggestions you just outlined but could never completely correct the problem. I now see that this made learning to sail the first year more difficult. Not only was it difficult to properly trim the sails, with too much weather helm you can't feel the rudder though the tiller which makes steering diffecult.
With the mast step in the current location the mast is raked more forward - I know this only because when the mast was stepped last spring the backstay had to be let out significantly for the clevis pin to fit. Now I can feel small changes in water pressure against both sides of the rudder when I move the tiller. Now I can steer a straighter course and adjust with changing wind pressure - this is a huge advantage when learning to sail.