This is a great article. I have constantly been questioning where I will write when our family grows. At the moment I have a spare room as a study but as you said I may have to sacrifice this space.
Whilst reading your article it came to me we have an under the stairs cupboard which is storage space. I can now change that into my writing space.
I also like one of the comments on your article about using a backpack. Both ideas really appeal to me.