FYI, LSI oems their PCI brackets from Purcell. So theres a chance theres a corresponding Purcell blank in their database for the SFF-8844 opening, but you'd have to find it.
http://www.cbttechnology.com/products/Purcell/PCI/purcell-blanks-database.php
Keep in mind they're a wholesaler and generally don't deal with end users and one-off quantities. I dealt with them before for an order of 100 full height brackets to outfit a gaggle of bracketless M1015's, and I got lucky they dealt in a quantity that low - did me a favor and sold them as factory samples, plus cost of shipping from H.K.
Short of finding the Purcell equivalent (a custom-run isn't worth the cost) and managing some kind of group buy then probably the vented bracket getting hit with a file or dremel tool - or yes, high powered military grade laser - is the most cost efficient.