Limiting Amount of Nights for a Stay?

Does anyone know if there is a way to limit the amount of nights that you have on one stay? I don't mind doing overnight stays for up to 5 nights, however, besides saying you're not available on certain days so you can take a break, does anyone know if we can limit the stay requests that we get to a certain amount of nights? I've had 3 week stay requests before and hate saying no, but have my own dogs & other responsibilities that I need to attend to.

TIA!