I think I'm literally the only one with an Air 540 part from ColdZero at the moment since I was the one who kept asking for him to make some parts.
Best bet is to head over to the ColdZero forum and create a thread to ask him. Im sure Ricardo will be glad to help and provide a picture of the midplate.
I think thats because its too expensive! - £50+! woot!
I do note however that Ricardo has now made some midplates specifically for the 540 which cover the drives at the bottom. I would have ordered one if it wasnt for -
A)- The fact delivery is nearly twice the cost of the product to the UK!
B)- You can only install the plate with SSD's in the drive bays (theres only like 13mm clearance)
I'd link but it might be classed as a competitor, sorry guys - google is your friend