There are cable-actuated/hydraulic combo rear calipers available from Wilwood.
There are also standalone mechanical calipers. Both of these solutions require someone to fabricate a single or double caliper mount. Yes, you could have a parking brake setup separate from the service brake.
Even though it weighs a ton, the hydraulic/cable Golf(or Volvo?) rear caliper EVERYONE uses works and works well, most of the time.
This rear caliper is also used by Pete of Airkewld, who makes some of the lightest and highest quality brakes available. I have them on all 4 corners.
Be aware that you may have squeaky brakes if you use Wilwood calipers/pads. They are not domestic/production line type parts. I don't know if they require more maintenance(mine haven't) but OE/production car reliability cannot be expected.
Also, while lapping LRP at a 1900 pound curbweight(heavy instructor) my Spyder never had fade or overheating into turn 1-2(Big Bend) from 120mph.
If you end up using a Wilwood caliper, someone will most probably have to fabricate a caliper bracket, as Wilwood do not sell complete kits as Gordon states.