Back when I was an Amiga dealer, we solved this problem in a couple ways. We got some flat aluminum bar stock from the hardware store - about 1/2" wide and maybe 1/8" thick.. Then we'd bend two pieces each the depth of the 2000 with about a 2" 90 degree bend on both ends. The back ends would get bolted to a blank card slot cover and attached to an empty ISA slot opening. The front ends would be bolted into the front of the case after removing the plastic card guide.
Some of our customers made their own brackets using that channel stuff used for adjustable wall shelving... whatever works...
If they needed a lot of drive space, or if they needed more than one 5.25" bay, we'd sometimes make an external drive box out of an old pc case... nowadays, I'd look for a surplus mac external HD.. I've got two of those on my own Amiga.
One time we did something really unorthodox. There is actually enough room to mount a slimline (all of them now) hardrive on the outside of the 2000's frame in between the metal front panel and the outer case.
