Great setof links there Becky! Personally I'm tempted to try to follow the directions on that first one, where you put a small little night light type lamp inside a styrofoam box, and put the feeder in the top of the box to hang. Looks a little ungainly, and could use some sprucing up, lol... but I bet that would work really well and wouldn't mess with the hummers usual feeding habits.
My birds would likely refuse or never even find a box set up where the feeder is inside the box, and I've heard some scuttlebutt where folks are concerned that heat lamps and such may mess with their ability to deal with the cold? I dunno, but it does seem like keeping things too warm may end up causing more problems than its worth.
The plumber's tape is easy to install too, and is available at a reasonable price online. It would also be easy to remove if you use electrical tape, later.
As I have said in other posts, here in my old house with uninsulated, 30 year old windows, I just hang a window mounted feeder on the window, and the radiant heat from the window keeps the nectar warm down to around 22 degrees, with room temps up around 65 daytime. I've actually had them stay liquid lower than that (down to around 18 degrees one bitterly cold winter, well, for us!) but we upped the heat in the house at that point too. No power, so we were trying to heat the whole house with a wood stove, I think the inside temps on the window were up above 80 shrug
At any rate, there are lots of various solutions for this. Get creative and if you anyone comes up with another idea, please post it!
USDA zone 8b