In my ubiq, I used one extender cable "as is", and one spliced and soldered to - around - 60 cm of length (24" or 2 feet, for the metrically impaired).
I see no differences in lighting from the two lamps.
The extension cable was copper cable for house electrical grids, with an insulating coat rated for 500 volts (being an engineer, I know it should be safe for at least the triple, or one of my colleagues need to change job; OK, I didn't,t trust it, so I added something, just to stay sure) and a conductive core that was - roughly - the diameter of the whole extender cable, coat comprised (so, even if the extenders cable core was silver, and not aluminum as I think it was, its specific resistence should be less than a quarter ).
I also had the luck of having some bigger cable, whose core had in turn roughly the same diameter of the extending cable, whose insulating coat I removed to use as a tubular isolator around the junctions.
By practicing a circular incision in it, at about 5 cm of length, and then pulling the core out, without damaging the coat, you can have small isolating tubes. They are a very neat (though a bit laborious) alternative to the tape.
I cut the Extender's cables, one at a quarter of its length, the other at three quarters (or vice-versa; the important thing is that, this way, the junctions are not phisically near to each other) and unsheathed the extender's cable core, for an eight of its length, on both sides of each cut, by making an incision along the length of the cable (give its meager conductive core, a circular incision would have meant a risk; also, in all it's a couple of cm) and then removing the insulating wheat.
I pulled my copper cable inside the aforementioned coat pieces (the play of diameters was just right... the copper cable slided inside with ease), then provided to practice a similar, longitudinal incision in its coat, slightly longer this time, an only bending the coating backward, without removing it.
I opened the strands of both conductive cores, and meshed them together trying to avoid irregularities. then, I twisted close the junction, and soldered it.
Capillarity sucked the solder tin nicely inside the reconstituted cable, so that the junction seemed just a piece of monolithic cable of a couple of cm of length (4/5th of an inch).
I placed back in position the sheat, and than slided the "isolator tube" on the junction, so that it covers it - as the core has "fatten up", it required a bit of an effort, so it is not going to come loose.
I did the same for the four junctions needed, though with the alteration that I pulled one of the two cables inside the external sheet of a coaxial cable (just to reduce the possibility of parasitic capacitances).
I know that, to reduce possible RF interferences, the antenna loop that the two cable constitute should have area zero (using a twisted pair or a coaxial), but I also read somewhere that stacking the ccfl cables too near to each other may negatively affect their performance (losses through the isolator, or the highest harmonics of the PWM signal sucked into capacitances? that's the question... - OK, it' s official; I'm obsessed by unwanted capacitors).
As I said, I do not see differences in luminosity between the two sides of the screen - one extender vs one extender with 2 soldered intermediate junctions -, so I suppose that the results were good.