Well I don't know what you would do then for a dummy load?

If your talking the standard mini twinkle type lights everyone normally uses, they are usually 1.5V or the super brights I think are 2V.
I think if it were me I would just run those 5 lights on rechargable batteries or a wallwort transformer. They sell those strings of about 5 and 10 lights that run on batteries.
 The little spinning motors to rotate ornaments are the same volts also since they plug into the light sockets normally.

I don't have any handy to test with but I think you could just cut off 6 sockets/lights already wired in a row and use a 12V wallwort transformer wired to the set. If you try that, run it for several hours (or all day) laying out safe and check for any heat problems with wires or the wallwort. I do that kind of stuff all the time with twinkle lights but not exactly what your doing so test first. You might want to try 8 lights first incase you have the 1.5V bulbs, if they are dim then cut off one at a time till you get the correct brightness. Or just test 1 bulb first on a 1.5v battery and see how bright it lights.

Of course the wallwort transformers come in all kinds of powers. If you have one laying around from a junk scanner or printer it should probably work ok, just match the volts for the lights to the transformer in case you have 9V or 12V, if it can run a scanner/printer it should have the amps to run a few lights. Beware of those wallworts for things like cheap speakers and such, they are often low power and may NOT run the lights. It should have the amps  or miliamps listed with the volts on it.

Anyway that's what I would do, either rechargable batteries or a good wallwort transformer.
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nothing to lose