A similar plane, the Sopwith Tabloid had these characteristics: | During official trials, the Tabloid achieved a maximum speed of 92 mph, with a stalling speed

A similar plane, the Sopwith Tabloid had these characteristics: | During official trials, the Tabloid achieved a maximum speed of 92 mph, with a stalling speed of 36.9 mph. https://www.ctie.monash.edu/hargrave/sopwith3.html https://www.ctie.monash.edu/hargrave/sopwith3.html You have a lot of good points above but missed out of a great way to reduce stall speed: less weight! As you burn off fuel or otherwise shed weight, your wing loading decreases and thus you are able to decrease your angle of attack for a particular airspeed. Of course, angle of attack is the key to a stall (and thus a spin) so we can talk about other ways of reducing the angle of attack, often by unloading the wing. Eg: another way to unload the wing is to reduce the tail-downforce that the main wing needs to counter in this classic design. By moving the center of gravity as far aft as is practicable, you achieve the same goal. As with anything in aviation, this is a trade off; By moving the CG aft, you make recovering from a stall harder or even impossible. I imagine that stalling in one of these bi-planes couldn’t have been a benign experience to begin with so, pilot beware!