I don't get why a note needs to be left at all? Put it on outside of door- maybe someone finds it before you're gone. Letting them know you're in there- what if you're not gone yet? I'm sure it's not totally uncommon for people to ctb in hotel rooms, so the trauma may not be so severe (yes it will impact the person). They'll know to call police. If it brings you comfort to leave a note then you need to do it for you. It's all about having as little anxiety and pressure on you as possible. Be well.
I definitely don't think anyone should put it on the outside of the door! Still- most hotels provide a chair don't they? Doesn't seem much effort to write a big note, place it on the chair and place the chair on the inside of the door- blocking the hallway/entrance.
I just think that the fewer people are impacted- the better. Maybe police officers are accustomed to finding dead bodies but I doubt a school leaver is- housekeeping jobs are usually badly paid- we really have no idea who will find us. I know it likely happens a lot in hotels but I think there are things we can do to minimize upset. Taking plastic sheeting along is also something I would do.
I'm lucky enough to be able to do it at home but I still intend to make it as less messy and less traumatic for the people (likely police) finding me as possible. I do understand that some people are in a very distressed state when CTB- so- might not be capable of a whole load of planning but I imagine someone booking a hotel and buying all the items needed to CTB has already done quite a bit of preperation. Doesn't seem much more to try and limit the impact on the staff and hotel.