Some chicks won’t tolerate slings and may fight to get out of them, but many tolerate them. Take her out to sleep and rest often. Let us know how she gets along.
You could try to get her drinking fluids with electrolytes. Gatorade works and you can make simple homemade electrolytes. Mix a little wet chicken feed and offer. A chicken sling would be helpful if she will remain in it for periods to get upright and sit in front of food and water. If her neck...