OK. So I'll have to make do with adding an image onto the phone and setting it as the background/wallpaper. This lets me see how much the image is cropped. I can then edit the image on my PC to add the text box whilst looking at the image on my phone's background to GUESS a position that will not get cropped. I can then export the image as a jpeg, send it to my phone and set as background.
Not the best but it works.