PD, OK, I think what you are saying is that the debris may have accumulated in the bowl during normal use and not the evaporation process? If so, might not draining the bowl from time to time help to get rid of some or all of the debris?I will let you know how the evaporation expiriment comes out, may take a while. I have used Berryman's B-12 fuel additive for years which is supposed ti absorb moisture? I have never seen any water in the bottom of my various fuel tanks. I will try another expiriment, put some gas in a container, add some water, then add some B-12 and see if the water goes away?
I did a study for Practical Sailor Magazine a few years ago. NONE of the additives had ANY material effect on e-10 separation. They may do other things, but they DO NOT prevent separation. Just snake oil. They did work, to some extent, on non-ethanol gasoline. However, some of the old "dry" additives have been proven to make separation in humid conditions worse! They were ONLY for winter use, to prevent icing, when the humidity is low. But the advertising didn't say that.
Yes, I suspect you were getting occasional e-10 separation. The best cure is to keep the tank full and the vent closed when possible.
I doubt draining the bowl is fast enough to remove any debris. Removing the bowl and cleaning every few years is very easy on some small engines (I've done it on my 3.5 Merc while the boat was hanging over the water on davits! I also added an in-line paper lawn mower filter.) and might make sense.