It might be worth looking into finding a low melting point eutectic mixture, I looked at that once when I was contemplating building some sort of downs cell modification, and as I recall, I think there was a eutectic with one of the salts of gallium that had an MP of 80 odd degrees, which would be easy using a blowtorch.
Dry your NaCl over NaOH for a week or two maybe, just to make sure that its anhydrous, or heat for some time before adding the metal for the reduction, maybe you could use some of the Li from the batteries you were taking apart, probably wont matter too much it its a little oxidised, if that is, Li is a strong enough reducer to tear apart Na from its compounds.
On second thoughts, why not simply go for the electrolysis of fused NaOH, I have had OK yields of Na from this using a car battery, use a blowtorch to heat the NaOH and keep it fused, or better yet a camping stove and dig out the blobs of molten Na with a spoon as soon as they form then chuck them into naptha or other light hydrocarbon to store them.