If the hotel discovers that the room is unoccupied, they will almost certainly check you out. This is done to avoid billing problems. Hotels don't like charging guests for a room they don't physically occupy because they will probably lose any chargeback if the guest can prove they were some other place. (Note: This doesn't apply to non-refundable reservations.)

Additionally, some hotels are required by local law to conduct a "welfare check" if they don't have any contact with a guest after a certain number of days. Other hotels will do this absent of a local law. It's a bad situation for everyone involved if a guest has fallen and can't get up to call for help.

It should be an issue if you tell the Front Desk upon arrival that you need the room but might not be in it much. No need to get into specifics...most employees at hotels aren't interested in your reasons why. Certainly, decline housekeeping service.

Personally, I'd put the "Do Not Disturb" sign on the door. Then, on your departure day, simply call the hotel and say that you left but forgot to take down the sign.