Darn good question. I never thought of an extension. I was just about to order a 274cm (9'), or probably a 295cm (9'8") paddle here
http://www.wavewalk.com/Fishing_Kayak_Paddles.htmlEither of those would work better for lower angle paddling for us taller guys, or for kayaks with more freeboard, like the ProAngler/Outback especially with us taller guys.
However, an extension to my existing Hobie Paddle would be a lot better, since I rarely use the paddle, except maybe for standup anyway.
Though I have an Outback and am fairly tall, the ProAngler/Standing up/FlyFishing, and a longer paddle are like coffee and creamer. Hope they suggestion takes shape..... If not, guess I'll discard my Hobie paddle, or try to make a home made extension, or buy one above.