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.
* A typical rack is rated for somewhere between 450 and 900 kg (your mileage may vary).
* A disk is about 720g.
* A 4U quanta enclosure is 36 kg empty.
* With 10 enclosures of 60 disks, that's a total of 792 kg inside the rack.
You will want to check what rack you have exactly and weight things up.
The rack itself is another 100 to 200 kg. You will want to double check whether the floor was designed to carry 1 ton per square meter. It might not be.
My personal tip. Definitely do NOT put a row of that in an improvised room in a average office building. You might have a bad surprise with the floor. ;)
Anyway. The project will probably be abandoned after the OP tries to assemble the first enclosure (80kg fully loaded) and realize he's not going to move that.
That seems rather unnecessary risk. Sure you stripe across the racks but another tor switch in mlag configuration is a minuscule expense compared to the costs involved here
You could easily run two switches, there would be enough room. But normally yes, I'd run one switch per rack. Switch failure is pretty rare, and when it does happen it's pretty easy to switch it out for a spare.
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.