I have seen and wiggled one of the hera rods but I have not fished with one. It seemed surprisingly stiff and I am not surprised that yours wouldn't cast a fly with a light tenkara line. Daiwa and Nissin both make poles (not quite the same as what I think of as "hera" rods with their teardrop grip) that are designed for carp - although relying on Google for translations is questionable. I wanted to try the Kiyose 53MF and maybe even the longer 63MF first because I think they will work and they both collapse to a convenient 21" length. The poles intended for carp only collapse to about 48" but I may have to get one in just to see what it is like. I had looked at the Daiwa "Liberty Club" but chose the Kiyose because it is much lighter weight and also has the added feature of the zoom capability.
I have had to use two hands before with larger fish on tenkara rods, but had both hands on the grip section rather than one on the gip and one higher up. I am sure that John is right about needing two hands to fight a carp with the 53MF Erik was using, although it might be safer to have both hands on the grip section rather than one on it and one on the next section up.