Neil, I like you, you seem like an alright sort for the most part. However, this shit can not go unmentioned.
I live in a house as my knees and brain function normally. When I'm downstairs and need a piss or shit, I use the downstairs toilet, or cloakroom, if you will. Similarly, when upstairs and need to relieve myself, the bathroom is where I do my business.
And if I want a wank, whichever floor I'm on, I just make sure the curtains are drawn and the dog isn't watching, he kills my vibe.