Does it work for you to select all the objects with Control-A (or rubber band select), and use the arrows in the corners of the selection box (with Control held, to preserve ratio), or by changing the numbers in the height or width boxes (with the lock icon locked, to preserve ratio)? And then use Control-Shift-A to align the objects (remember to 'treat election as group') where you want them relative to the page boundaries, for example centered in both axes?

—Arlo