For that kind of mileage I'd set up some free barrels, stir in the gasoline, let settle until needed and just skim off the top and into the tank. Chances are you'll plug an onboard filter anyway as has happened to most WVO and WMO user I know. Leave the last 5 inches or so in the barrel for the next batch. FWIW I pour clean compressor oil straight into my tank when we change it at work, never had a problem. Upflows, CF's, and staged filters are aimed at much larger quantities of fuel. You only need like 100 gallons a year. Upflow IS controlled settling. Settling after blending should work great all by itself IF you skim the cleanest fuel from the top of the drum and don't disturb the crud on the bottom.