Has anyone ever experimented as to how long it all starts to separate?
There is no reason for petroleum distillates to separate, so if you left your blend in a sealed container for a few million years you should end up with the same blend.
Also, there is no reason to agitate a blend of petroleum disitillates, because they readily go into solution within mintutes and will remain that way until they are fractionated.
However, a 275 gallon tote is not pressurized, so the light fractions could be evaporating off slowly; however, a few weeks should not make a difference, as long as you are not storing your tank in the sun.
I regularly make a batch of fuel that sits in a black tank on the back of my van for as much as a month before I filter it into the fuel tank, and have had no problems; however, I do have a pressurized fuel tank cap on my processing tank, so it keeps the contents under pressure, and thereby reducing evaporation.