You can use Tyvek for making a sail. Its the stuff used in construction of houses. You will know when you see it. Making the Tyvek Sail
and many other websites. The mast you are talking about seems way big .. Might take a look at some they sell and copy them. pvc pipe ? You might only need a main sail or only a jib. and
has every little accessory you need and sail material of almost every kind. Also, will help you with creative ideas.