Mac Pro low profile card in standard PCIe slot

Such a simple thing....

I am fitting a low profile RAID card into my 2008 Mac Pro. The bracket is low profile. So I have three options:

1. find or adapt a standard profile bracket that fits

2. use a riser to convert the card to standard height

3. extend the bracket to fit a standard slot

1. The card is a Areca 1882i with a rear ethernet port. If anyone has a standard profile bracket for this please let me know!

2. None of the risers I have seen are the correct height. Standard height is 120mm, low profile 79.2, so a riser would need to raise the card by 41mm.

3. This seems the simplest, but I just can't find the adaptor. Here is an example. You'd think this was a simple thing to find, but no luck at all.

Any assistance much appreciated. Thanks in advance.