If you need more depth, consider doubling up two identical mesh wire type shelf/racks.
They should butt up perfectly/close enough for a nut/bolt/washer pairing or use some cheapie G Clamps, duct tape, poly string, thick cable ties etc
If the wire mesh shelves are too flimsy or wonky, put one-piece overlapping wood boards on top to span both racks,
drill up some holes and stick some thick cable ties in there to secure the lot.
OR...
The wood boards can be modded up to hold the paired racks together in the center and or edges,
so no nut/bolt/washer or G Clamps required,
and easily removed for future height changes or re-locations etc (please excuse my twofer come cheapskate methodology
)
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FWIW: A lot of affordable, reasonable quality, DIY racking here is 540mm depth
with 'stated' weight ratings of 400 to 450 kilos per shelf.
Two of those will give 1080mm depth, which should keep long HP and rack server owners happy enough,
with some change saved for a beer or two afterwards,
...or for another Ebay 'not working/for parts only' deep format test gear acquisition