I also use the black plastic pipe.
The technical name for it is; HDPE Type S (high density polyethelene, smooth liner).
The two biggest manufacturers are Hancor and ADS.

A 12" pipe can easily hold two sets of sails.
A 10" is big enough for one set.
I prefer to have a second 6" tube for the boom, tiller extension, spare tiller extension, and spare tiller connector.

I have a truck toolbox($80) mounted on the tongue for the bulky items.