i have the same model.
i went to the store and bought 5 of the 2.5 gallon drinking water dispenser things (kinda rectangular boxed shape with a spigot) and drank all the water/cooked with it, etc over the course of a week.
then i took and set up the ro unit in my bathroom. i enlarged the venting holes on top of the water containers a bit so the water feed would fit in it.
maybe i was lucky, but the water containers fit in the bathroom sink fairly well.
then when i left each day for school, then work, and then when i went to bed, i started another container filling.
took me less than 2 days to get the whole lot full up, and now i have 12.5 gallons on demand through a spigot for water changes. i do about 5 gallons a week, so this is a great ammount for me.
just be sure if you go for a slower system, if you want to leave it on over night that you fill it in a sink or bathtub, because it will probably overflow while you are alseep, flooding everything.
if you do larger water changes, i know there are 5 gallon containers out there for the drinking water dispensers (alhambra and what not) that you can get if you need to store larger amounts.
HTH