Forgot to mention - in my opinion the Hyperion motors are great motors but that particular one is way more than you need for the Mirage. That 3020 weighs 175 grams.
Im using a hacker A20-20L which weighs 56 grams. Im using a 3S 1100 pack, 11x6 folding prop and pulling about 220 watts static. Thats enough power to compete very nicely in ALES competitions and more than enough for sport flying - while still keeping the models all up weight very low.
Build it light, dont add any extra structure, dont beef up the spar, use a light weight power system and you will end up with an outstanding model.
Of course, even if you build it a little heavy, the Mirage will still perform very well. But why build a model with permanent ballast you cant remove?