I wear a half-wig 90% of the time. I put a plastic cap on first (the one from the BSS used for deep conditioning) then, I put a men's satin-like skull cap over it (it's like a doo-rag but it fits like a scull cap). I try to make sure that the plastic cap covers my nape area and that the skull cap holds it in place. During the day, I have to adujst the plastic underneath, to make sure my nape is protected. The skull cap does a pretty good job of covering the plastic cap and keeping it in place.
The benefit of wearing both caps is that I can baggy with the plastic one, and the skull cap acts as a barrier between my hair and the wig. HTH
I wear a small thin silk scarf first and make sure all the small hairs around my hairline are covered, then place the stocking cap over that. Works well so far ...
I use half wigs or will wear whole wigs as half wigs. Instead of the wig caps I use those very think silk like sleeping caps to cover my hair. I can put a baggie on up under the silk cap and not worry about anything being too tight.