Mike,a 12 x 5 will fly it fine. 100 plus was clocked with my Venus and a OS 50, but the Aresti with a OS 46 FX was faster.

Paul, I did not see a need to add any bracing to the tail.

To anybody concerned with landing speeds and this plane, fly it a few times and you will get it slowing down. Just keep it out of the power lines.
Ed M.