Glitch,
I will try to answer your statements one at a time.
1) Regardless of engine size, I do not believe that it is worth the chance of engine damage. A couple of dollars wasted on gas verses hundreds in possible damage. Does not make sense to me.
2) If the manufacture recommends 40:1, less oil more gas, (which is a richer mixture than 32:1, more oil less gas) and/or your bike has been re-jetted to accommadate the 40:1 mixture, then that would explain why you foul plugs at 32:1. This would be an oil foul and not a carbon foul. Other factors that play a part are the condition of the engine, electrical components, quality of oil used, amount of octane in the fuel, along with temperature, humidity, and altitude. There are other specific influences, but I'm trying to keep this short.
3) If a bike is running lean or rich, you can change the mixture to account for this without changing the jetting. But be warned. Less oil is not healthy for a bike. This oil is providing lubrication. Better to re-jet than to run less oil.
4) Lastly, this is not my theory. It is based on facts and is supported by web sites from companies, professionals, and experts in the field. I figure that they know more about these subjects then I do. You can either take thier advice and apply it to your conditions or you can blaze your own trail and take your chances. The choice is yours. My choice is to use the expert advice that they offer.