Acetone is a dry'er, often used instead of the brand 'Heet', and/or others, and cheaper, i.e., one buys a gallon at the hardware store, using a turkey baster, (for example), in order to insert said prior to fill-up.
An ounce, or two is often used at fill-up in order to dry up any small amounts of gasoline that has an extra amount of water going through the station pump, and/or condensation dripping from the interior ceiling of tank, etc. I often do the above, and find better performance, and mileage results.
I do use SeaFoam every other fill-up, i.e., half a can at a time.
I also use an ounce of 2-stroke oil on each fill-up.., straight from the plastic bottle.., for upper cylinder lubrication.
Small amounts of the above liquids seem to work best as for regular maintenance.., but not used excessively.
Your varnish issue seems to require a couple of extra fuel filter changes during your process of eliminating the last traces of varnish whilst using bottles of magic.