I've put 39U of drives in a rack before. You only need 1U for a network switch, and you can get power that attaches vertically to the back, so it doesn't take up any space. If you have a cabinet with rack in front and back and all the servers have rails, the weight shouldn't be an issue.
The biggest issue will be cooling depending on how hot your servers run.
Specifically, it was a rack full of Xserve RAIDs, which are 3U each and about 100lbs each. So that was over 1300lbs.
