Your EMax should work just fine. Prop with a large diameter prop if you're going 5 cell. I'd use the 14x8.5 or a wood 15x7 for 3d and slower flying. On 6 cell the 13x6.5 or 12x8 for 3d and slower flying.
I didn't use the joiner. the leading edges weren't the right ones so I had to cut them off and install new stock so I went ahead and used a wire joiner and drilled the holes in the elevator, then just twisted the joiner until the ele halves were even and epoxied afterwards.

I still don't know how you are so tail heavy. If you aren't installing a spinner, buy one, it will help the forward weight a bit. I have my ESC on the front of the fuse opening into the cowl below the battery box. My 5s4000 mah lipo pack is pretty forward to balance but isn't touching the front box wall. Remember that spinner, prop, and cowl all have to be installed for balancing.