I provided a 15° wedge shim to angle the gear back. It looks bad and only reduced the weight on the tail wheel by 6 oz (half what is needed). To do that is not the answer or a reasonable fix. I expect what is needed is to move the mains about half way from where they are at towards the CG. Unfortunately to move the gear mounts internally would require significant effort so it might be more reasonable to move them externally.
To do so, it might be possible to mount a 1/4" aluminum plate in the stock holes that extends aft the necessary amount to provide a new mounting location for the gear. I estimate that the wheels should be moved aft between 2-2.5 inches.