Mike -
I'm just curious why you want a longer rod, instead of perhaps casting a longer line ??
With my TenkaraUSA Ayu, I have fished about 30 feet of line, in the form of 20' of the running line from a WF5F fly line plus a 10' Tenkara line / leader plus tippet. ( If you go through the "sticky" Tenkara thread at the top of this Forum, you will find several posts on this approach. )
The problems with that set up are that you can only fish the "outer reaches" of your maximum casting distance and you do have to do quite a bit of hand lining to land a fishy.
Just an idea as an alternative to buying a new, longer rod.
John
The fish are always right.