Rhezz,
According to Freudian (Fraudulent) shrinks, you must have a real desire to expose your inner self.
Anyway, I suggest you get yourself something of the same approximate size...like a HEPA air filter, from boots directly....stick this in your room, and when nosey MIL asks what is in the box, you answer...an air filter...and then take it up to your room...or maybe you should just tell her: MYOB!...and eventually tell her about the air filter.
This is what i'd do in your circumstances...unless, for example, you don't mind getting a large stuffed toy or something...
Dill Pickle