No idea what ya'all are using for back end hardware (leased, rented, own your own whatev) in any case if it comes up useful...
I have a pallet of Supermicro server chassis that I am never going to use. These are open chassis (no mandatory power supply etc) which support 48 internal mount external access hard drive bays. So 48 available hot swap bays. These mirror up to a few cards very well and basically any hot swap compatible raid cards will work, just a matter of making sure you can make cabling work. It supports port to port, port to bay or port to bay grouping cabling and I think I have all of the above that works with Areca cards (I may even have a spare Areca I can toss in if it is useful)
I have one of these humming away and swapped out the mb to a low poer Supermicro server board that dropped the concurrent draw to about 150w but that is because I have it mounted in a rack at my house, wanted to keep from over-loading the service here.
If you have use for such I will donate it shipped to the lower 48 my cost. Consider it sheer gratefulness for being accepted into an awesome group.