Wing Extensions for my plank

Added these plug in wing extensions to my 1 meter plank to make it 1.5 meters. They plug inside the ends of the 1 meter wing and then are held on by tape. Feel very sturdy and little flex. Haven't tried flying yet. Made from 9 mm epp, then laminated then added couple barbeque spit spars. Each extension weights 50 grams.
Wanted to get more soaring time but still be able to fly 1 meter wing aerobatically without them. Also will allow me to test out different wing tips
AUW is 640 grams now with little 2208 1800kv motor - should still fly.
Update Oct 12: It flies. I was afraid it would be too heavy for the motor but in fact I had to back off the throttle to keep it under control. Tons of lift and in poor conditions, in the lee of a building, on a tennis court and in gusty wind. It also still banks sharply, I was afraid the now inboard elevons wouldn't work so well but they do. Just wanted to know if it would lift off. Sunday is supposed to be fair weather.
Update Oct 13: Took it out today and floated it around way up high to take some video of the school. Real floater and can be flown very slow.
Update Oct 18: Trimmed extensions a little to be more aerodynamic. Wing area = 511 sq. in., AUW 22.2 ounces for WCL 3.3. It really qualifies as a glider.