+1 to a leveling base of some type - it makes everything else easier. A really strong head with a panning clamp will make it a lot easier to start level and take control of one axis. Then you can add a rail to hit the nodal point, a swing arm to do multiple row captures. By any chance do you have a gimbal head for your tripod, as these can also be be used with a rail to achieve 2 axis nodal.
Let's take a step back and see what you're trying to do. Are you doing this for greater resolution, or for framing purposes? How close are you to the nearest object in your shot? Ignoring a perfect shot, have you tried just panning left to right capturing multiple shots & stitching them? Does one row of portrait orientation give you framing that you want, or is it not tall enough? How many shots wide did you shoot (assuming a good amount of overlap between them)? If it takes more than 2 row of portrait orientated shots to get the view, you are looking at a different 2 axis type panorama kit.
I think the cable releases for the DF/DF+ is a physical, not electrical release, so an automated head like a Syrp or Gigapan wouldn't work. Have you looked around for a manual focus M645 lens like the 45mm f/2.8 - it may hit your needs without the extra work of stitching.
-Joe