I mentioned this on another thread, but I'll also mention it here too. Changing the dpi shouldn't make any difference.
For example, I save my 8x8 inch layouts at 300 dpi which is 2400 by 2400 pixels. When I change it to 72 dpi, my 2400 by 2400 pixels don't change, but the *inch* measurement does. My layout becomes 33.3 x 33.3 inches. Of course, all of this is 'behind the scenes' - the layout doesn't suddenly appear to grow because as you know, we are working on it in a reduced format to fit on the screen.
The only was to make it smaller is to reduce the 2400 pixels which I do. I make the layout about 700 x 700 pixels which is generally under 125 k [depending on number of colours and textures in the layout]. The mode of presentation determines its size in inches. On a screen at 72 dpi that is about 10 x 10 inches. My screen is actually at 96 dpi so it is closer to 7 x 7 inches. On my printer, it is very small since my printer prints at a much higher resolution.
I hope that helps in removing an unnecessary step...
