What is the ideal method of supporting a 27" deep floating desk across 10 feet of wall?

I’m building a floating U shaped desk in my office that will go from wall to wall. This desk will need to support the monitors and accessories of two desktop computers. The towers will be on shelves closer to the ground out of the way.

I would like it to be 27″ deep along back wall, which is 10′ 7.5″, and 24″ deep along the arms, which will extend 4′ out. The finish surface will likely be cabinet grade pine plywood, 1/2″, sanded and stained a nice color. I will fabricate the surface using two sheets of plywood, cutting a 69.75″ x 48″ outside dimension L from each sheet.

I’ve spent hours searching for something similar to this, but common sense would dictate that the deeper the shelf, the harder it is to use small and concealed support. Another concern is preventing the plywood from warping under load. So far the best advice I’ve received is to use flanges and threaded pipes on every other stud all along the underside. Either that or spend $30 a pop for a few granite counter top brackets. I would like to avoid that.

Using an in-wall bracket is not an option as I rent an apartment. I have no problem patching holes from bolts but I can’t go cutting into the sheet rock willy nilly. I would like to know if anyone has experience with this sort of thing or has any ideas that would work.

This is an idea i’m considering, using 3 different shelves. I would do the arms as 4′ x 2′ shelves flush to the corners of the wall, and a single middle shelf at 27.5″ x 27″. But I’m still worried that 27″ is too deep for support.