So it is 3/16" off one tip compared to the other tip? That'd be 3/32" each side.

You're not screwed. I'd fly it and see if it shows up in flight. You'd see an elevator couple. When the elevator was deflected up, the plane would yaw in one direction. When deflected down, it's yaw in the other. If you don't see that at quick, max deflections, it doesn't need fixing.

It is easier to fix now if the fin/rudder aren't on. And probably would only take slitting above and below the stab on one side. The slits would provide the space to move that side up or down. Then CA the closed slit, check to see you've got it level, then slip a filler in the upper gap and CA it. Needless to say, you'd want to iron strips of white to cover the slits, but I do that anyway to cover the stab/fuselage seams. (Airplanes last longer that way.) And it sounds like you won't need to do it anyway.

However, if you're not entirely satisfied with this advice, there will be no additional charge.