I want objects that are dragged outside of the canas area, and on to the grey area that fills the rest of the page, to still be visible. Ive tried googling this but I dont know what this grey area is called.
You can't make them visible. They're off the canvas, which is the visible area of the document.
Here's a workaround, however. First, place a rectangle as your background, instead of relying on the canvas. Make the rectangle the size of the canvas and the background color you want. Then,expand your canvas and set the canvas background color to transparent or another color. (You can use Modify > Canvas > Fit Canvas to enlarge the canvas to encompass all your objects.)
When you want to export the original area, set up a slice over the background rectangle.
Sure! Happy to help.