I plan on adding a V sail to my T13. They are quick and easy to build for very little cash. I figure I will just keep it stored in the hull and then set it up for the paddle back, if the option is available. If you have the space on your yak and some time go for it. I doubt you will find it part of your everyday yaking though if you are fishing. I think it's kind of fun just for the novelty of it.
Good Luck
Dan