I use here in my Connecticut location zone 6/7 a small plastic greenhouse that is opaque. The palms sit in a protected southern location, that receives all the possible sun, and has excellent drainage. I use no artificial heat. The lowest temperatures here the last 2 winters was about zero. I mulch with oak leaves and straw. Both palms- a Waggie, and a Fortunei receive some leaf damage, but no spear pull. Strangely enough during the winter of 06-07 the Fortunei did better, this year the opposite was true.

I used the trashcan meathod with artificial heat on my Windmill. This winter we had a low of about 13 degrees, but still had a spear pull. If I were you, I wouldnt do the trashcan. This year Im going to get a greenhouse to put over my new butia, and im sure it will do better then the trchy did.

The 60 watt bulb alone will not generate enough heat for you in zone 5. I used hay bales stacked up surrounding some of my palms along with a 60w bulb inside, but it only raised the temp 3 degrees. If you get down to -10 outside, your palm will be history at -7. And I'm assuming that if you're in zone 5, you can expect to get even colder than -10. Your best bet will to use a greenhouse along with christmas lights and/or a large floodlight or heating cables.