A 10'x10' should work just fine for you MrBill, if you have some appliances to store as well you may need to go a little bit bigger. Our storage units have a ceiling height of about 9 ft. so you have a fair amount of stacking height to work with
I'm just guessing but probably 10'x15' or 10'x10' if you don't have much stuff.
Thanks! Your answer is awaiting moderation.