Trying to work on my DA and I have short fat fingers. I have a GP100 and a model 36. The model 36 is much more manageable (trigger not recoil). My revolver skills are limited and was looking to hone them a bit.
You could try lighter springs as part of a trigger action job. Then you could work on more of a finger tip pull. You could also try grips that expose the backstrap for minimal set back from the trigger, unfortunately not an option on the GP100 grip frame design.
As mentioned, a bit lighter action can help, as can grips with an exposed backstrap.
You could also have gunsmith narrow and radius the trigger, which gives the effect of a bit shorter reach.
Something that can make a big difference is how you grip your revolver with your strong hand - your grip needs to be firm and high. When looking from the side, the webbing between your thumb and trigger finger should be at least even with and no lower than the nub at the top of the backstrap (see pics). Too many revolver shooters grip their revolver too low. In addition to control issues, it effectively lengthens the distance to the trigger.