There are many airplanes out there today operating at a T/W ratio of .25 or even less - like a maxed out B-747 for instance. Many of the Korean War vintage fighters and even some Century Series fighters operated at .4 to .5 (non-afterburner). We're all just used to highly powered model aircraft today. I once did a 50 pound twin ducted fan aircraft that operated at a measured thrust of 13 pounds installed. The drag of your configuration will probably be a more limiting factor in terms of climb, acceleration and speed.