What I'm thinking of right now is to move the rudder up about 1/8" and capping the top of the vertical stab to match the lines.
between that and rounding over the center block in the rudder it should clear. as a bonus it'll cap the end grain making the stab stiffer.

Extending the rudder back is a good idea but it would mean moving it almost 1/2" back.. 1/4" for the stab and another 1/4 for the elevator block.

option 2 is a bit more involved..

remove the center block and either run split elevators (somewhat ugly having 2 control horns)
or make a 1/8" music wire joiner mounted on the hinge CL with a brass tubing bushing as a pivot point epoxied to the stab.

I'll try the simple mod first.