Dell Precision 3650 card slots

Hello, I am interested in buying a Dell Precision 3650 computer and want to make sure my cards will fit in the case.

The motherboard has 3 slots, #1 Full Height PCIe x16 slot 1, #2  PCI-32 slot, #3 Full Height PCIe x4 slot but five bracket spaces on the case. 

This is what I would like to do, #1 Nvidia video card, #2 pci audio card, #3 Universal audio UAD-2 pci-e card.
That leaves two brackets for two daughter boards for the audio card. The daughter boards do not need to sit in a slot on the board, only screw in to the case bracket. Would this work?

Thanks for any help you can offer.