Is it permissible for a woman to uncover her leg when slaughtering, if no one sees her?

The correct view is that it is obligatory to cover one's awrah even when in seclusion, because the Prophet, peace and blessings be upon him, said: "Allah is more deserving that one should feel bashful before Him." The awrah of a woman is what is between the navel and the knee. What the sister who asked the question did does not involve uncovering the awrah according to this. If there is a need to uncover the awrah while in seclusion, it is permissible. Indeed, it is permissible for even the slightest purpose, such as cooling oneself or protecting one's garment from impurities.