I will now remove the CFL "light bulb" and place a full-spectrum LED in its place.
And now I see the solution. You donate nothing. If you have children, leave them what you feel like giving them, and preferably before you die (if you know you are about to die, that is a good time to leave it to the children). Nothing should be left for the Washtowel or anyone therein to steal. Add a clause that, if the Washtowel takes it, the heirs have grounds to sue the Washtowel for blatant and open theft of their property. It belonged to the children. Even leaving a small amount to the Washtowel is not a good idea.
If you do not have heirs, it's better to leave your property to the State or some regular charity (one not affiliated with any religion) than to leave it to the Washtowel. Again, using it to pay for your funeral, or to pay down whatever bills you run up while sick and dying, will help deprive the washtowel of any cut. If you are being assisted by a regular charity, leaving your assets to that charity will help repay them for assisting you. You might even have an arrangement for some charity to assist you, and you leave your assets to that charity. Just be sure your charity is not infiltrated with religion that could waste substantial amounts of funds spreading rubbish.
Even if this is not possible (in the case of sudden death), you are better off destroying your wealth or leaving it for the community to take than leaving it to the washtowel. Life insurance policies with the washtowel as the benefactor need to be stopped--cancel the policy at the insurer. If you die alone, and suddenly, it is better to leave the wealth with the community than with the washtowel. They need to be cut out of any arrangements no matter what. And, especially where heirs are involved--they come first, not the washtowel. If the washtowel isn't content with getting a modest share, they need to be explicitly cut out even if you give away your wealth to your children while you are still alive.
Taxes? I think it's better to pay gift tax than give it all to the washtowel.