Skelrad,

At that altitude you'll need a light wing loading for .40 power. I'd suggest rebuilding the Kadet, but the structure is not the most rugged (that's also why its so light and flies so good).

In your case of teaching your self to fly, keep with a 3-channel plane - Rudder/Elevator/Throttle. You'll have to learn to trim it out by your self, and the less controls to mess with the better. You can upgrade to ailerons at a later date after you learn to fly. You will also be battling the issue of density altitude where planes just don't like to perform. At 9000' even a .40 will struggle to develop power on these planes. With the altitude, the plane will still want to fly at say 40 mph airspeed, but the ground speed will be quite a bit higher compared to being at 500 ft. I think you really need to take a very close look at an electric powered glider. It has the wing area to help carry the weight yet keep the speed down. They are very gentle to fly and react slowly to control movements. When they stall, the don't loose very much altitude (your biggest enemy). And the motor will not care about density altitude, only the prop will (others who fly at high density altitudes may be better at helping you with props, but I think a larger dia may work better also).

The Duraplane has a span of 50" and weighs 5.25 lbs., the Hobbico Sturdy Birdy has a span of 53" and weight 4 lbs. Quite bit less in the weight department and a bit more wing area.

By comparison the BUSA Stick 40 has a span of 60" and weighs 5 lbs. It has a lot more wing area. http://www.balsausa.com/kits/kit.htp?id=36&shopperid=
A bit more weight than the Sturdy Birdy, but a much larger wing for a lower wing loading.

What every you do, take your time and do your homework. You're flying at an altitude most people will never see. I know when I fly full scale that the climb performance at 9000' has really degraded to a crawl. The same happens to models.

Hogflyer