Take a look at this rod. And to think I have been doing something very similar all this time...
"Two-in-One fly rod concept is used by the Czech competition fly fishermen for many years. The rod is basically four piece with additional fifth section used as the extender.
The 4-piece XP 9003 rod is a 9 ft long, 3-weight fly rod. The additional 16 inches extender between the third and fourth section makes 10ft rod. The extension section is without guides, so the adding or removing the extender is very easy, directly in the river, without threading fly line into the extender, then the rod lenght can be exchanged very easily.
The rod is beautifully finished, the guides are single-leg gun smoked. Hends XP 9003 rod is designed for French leaders and fly line AFTMA 2-3. The weight of the rod is only only 87 grams including the extender.
You will appreciate rod characteristics – in the shorter 9th version it is slightly faster, pleasant for nymphing and wet fly fishing, but also delicate for fishing dry flies. With the extender, the 10 ft rod is softer at the tip and supports fishing small barbless hooks. To carry the extender is simple, just in the fly vest or backpak. In summary, the XP 9003 with extender is perfect fly rod for all types of light fly fishing, for changing river profile, bank vegetation, changing for nymphing and dry fly. Just have 1 reel with 2 spools (fly line, french leader) and head to the water with just one rod! This rod is great for competition fly fishers, it saves time to run for another rod – simply add or remove the extender."
http://shop.siman.cz/index.html?pod=/_hp_rod9003.htm