I have a 2-1/2 gallon gas can that I use to pre-mix 2-gallons at a time... (I like to leave a little room in the can to shake it up!)
I use one of my kids 10oz apple juce bottles to measure the oil...
Everyday before I ride, I just top-off the tank.
(oil settles to the bottom, so I always shake it first.)
I keep a 2-1/2 oz bottle of two stroke oil under the bike seat just incase I run out of gas, I can pedal to a gas station, pour in the oil & fill it up!
(I live in LA, so there's a gas station every mile.)