Looks good I've got the pink shelf right underneath the tube, means I can use all the space beneath it. Here's some pics of mine Luna pictures by StarlightSerenity - Photobucket (Scroll to the bottom, thats what the cage looked like when I first got it, got more in it now lol). Luna uses the wooden house, underneath the pink shelf, sometimes and likes to sit on top of it to clean herself.
There are 3 little tabs on the legs of the Sputnik that should be pretty secure when you clip them to the cage roof. I have the old HH with the yellow corner shelf, is this what you would like?
Re: Hamster Heaven arrived!
I've got the pink shelf right underneath the tube, means I can use all the space beneath it. Here's some pics of mine 
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