Panning clamp- on its way, check.That's a good one, too as you aren't stuck with a dead center horizon when using T/S . My next decision is on the Wonderpana system that privatebydesign recommends. I'm sure I'll get it eventually, but $500+ on top of the lens isn't too practical at the moment.
Actually, I did some empirical research on this:
A. If you are using a leveling base and a ball-head on top of that- you can pan most flexibly.
1. You can pan parallel to the vertical axis and level with horizon (level base, level camera, pan);
2. You can pan parallel to the vertical axis and pointed downwards/upwards (level base, point downwards/upwards, pan);
3. You can pan at an angle with the vertical axis and pointed downwards/upwards (level camera with base, then tilt the base and pan).
B. If you are using a leveling head (a dual-pan head or a panning clamp on a panning ballhead or an Acratech upside down)- then you are limited to 1 and 3.
This is because in the first case, you have two ball-and-socket joints, with the panning mechanism in between. In the second case, you have only one. So it is more restrictive. Unfortunately, I am not tall enough to have a ballhead atop a leveling base on my GT2541- so I had to compromise.