Mine will also sit right at 40" including the foam. Since my tank is 3 foot wide and even I can't reach across that and down 24", I'll have to figure out how to build in front access.
I didn't get the 20k XM's from Mark. I recently saw a tank with 10k Reeflux(?) bulbs and really liked the natural color so I'm going to give those a shot.
-Mike