you could find a container that held around 2 oz of oil that would be good for 1/2 gallon. or a 1 0z container go to the station put in 1/4 gallon and pour in the oil. shake the bike to mix and motorhome telling your self don't forget to check the gas next time.
those ratios should all be 32 to 1.
Here something to think about get some amzoil good for 100 to 1 carry 1.5 oz of oil if you need to get gas use the amzoil and 1/4 gas to set you home.