I know what you mean by the "holy crap" factor, except I call it "gaze magnetism". I've seen even the plainest portrait subjects transform into Glamourpus. It's like Jekyll into Hyde, only prettier.
The Contax GB-B1 bellows shade still turns up every now and then, both new and used (hint: extend your search beyond the large North American dealers). A nice thing about the GB-B1 is that it mounts on the outer bayonet of the Contax lenses, leaving their filter threads available for use. It also has a sleeve for 75mm (3in) gel filters, and mask channels on the front end.
The LA-50 (50cm) cable switch (two-stage button with the same diameter and spherical radius as the on-camera buttons, with a locking slide; a tip-ring-and-sleeve miniplug on the other end) is slightly less rare than the GB-B1, and the LA-500 (500cm) slightly rarer. There are also cheaper generic cable switches of unknown provenance heavily advertised on eBay, said by others to do the job. I gather certain models of Pentax, Canon, and Hasselblad cable switches may also work.
You'll want a comfortable number of rechargeable 2CR5 and AA batteries, perhaps you already have these. Once you stop moving film, energy consumption will drop considerably.
You probably already know about RRS's BC645BG-L.
-H.
