Maybe it's line length that's my problem then. How long of a line are you using when fishing Tenkara in tight quarters? There are lots of places where I can't lift a 12' rod up without getting into overhanging branches, and since you can't reel up some slack there's really no way to fish some small streams (unless you stand way back on the bank. The length of the rod means you have to stay a fixed distance away from your target. Plus if you hook one and cant lift the rod up then bringing the fish to hand can be tough.)
I can fish a western fly rod in a "tenkara" way by just not adusting the line length. Plus, with a reel you can adjust the line length by reeling some in or letting some out AND you can do longer casts. I can't see how a Tenkara rod could possibly allow you to fish more water than a western rod, since you have those limitations.
That's not saying you can't fish with it, I think that going Tenkara means embracing some limitations that you don't have with a traditional western rod, and for me those limitations make it harder to fish small streams.