I wouldn’t be too worried about the strength (you’ll still have nearly 3mm each side) more that it make drilling accuracy even more important.They look perfect thanks
The next issue to solve is the wall thickness on the ply.....
Martin
Also you might need to cross drill for a couple of retaining screws, depending on how tight a fit/much clearance you allow.
And lastly you’ll not be able to rout any slots along the back as they’ll be interrupted by the metal brackets.
All points to thicker shelves to me.