This could be achieved by careful positioning of the motor, most likely at a 0 degree setting, with a rudder statically set to the right so at slow speeds it would turn right, a medium speed for straight level flight, and to turn left and climb a higher throttle speed. This is all in theory. There would be such a lack of control I doubt anyone would try it as a stand alone build but could be tried with an existing plane with working control surfaces to try it out and have those in case of the (i'm quite sure it will happen) inevitable need to save the plane
In the beginning of RC-control there was a one-channel class.
It used only rudder as control. The Class was called RC-III.
This is the competition path for year 1963 inkluding start turns and landning within a specified time span.
(seems like they got the flags wrong)
An old "friend" took an elevation record with a self designed 1 channel plane with a flight level of 1530 meter (5020 ft).
They used a following full scale Tiger Moth with a baragraph as a reference to measure the height. http://modellflygnytt.se/opublicerat/lo/index.htm
Back in the early '60's, a friend had a one channel non proportional rc plane. It had a glow engine. Trimmed to climb when the engine as on, when it ran out of fuel, it glided. The rudder was used to keep it over the field.
This thread reminds me of how it goes when my kids "discover" great new music from my youth like the Beatles, Beach Boys, Rolling Stones, The Who, etc. Sometimes it's better to just let them think it's new.
Why not a slope-soaring or high-start glider with just a rudder. Or how about a glider with something like a Cox .049, rubber band motor, compressed air engine, or an electric motor running off a capacitor (without a throttle), with steering controlled by a rudder. The engine would take it up, then the plane would glide back down once it ran out of fuel