I dont know how Dave did his but on my car I have fit the internal panels in following the line of the frame. Not resting on it but just parralel to it. Looks like it has given me an extra 3-4 inches of room down at the bottom where I'm toying with the idea of putting on a few of these for a little more storage
http://www.cbsonline.co.uk/product/L..._Pocket_STPOC3
I should have the car back from the paint shop this week so I will post a few pics before I start on the interior