I'm shooting with a 12' time lapse slider - it's the Dynamic Perception rig, but with two 6' sections fastened together.
Here's what a 6 foot setup looks like: http://3.bp.blogspot.com/_TufJDWGvofw/S_qBhLm2obI/AAAAAAAAApw/isYV1-0n4MU/s320/dynamicdolly.jpg
I want to rig the camera/head UNDER the track, and be able to "look down/ahead" the length of the track, be it a push-in or a pull-out. It IS possible to undersling the carriage/head setup.
The issue is, the camera will SEE the tripod, or whatever is holding up that end of the track. When it's not underslung, you just have to tilt the camera up a bit (like any dolly shot/push in). But for underslung, how could I rig the far end of the track UP in the air without seeing what is holding it? I've imagined C-stands with super long arms reaching in from outside the frame, or speedrail, or menace arms, I just don't know. Steadiness is a huge factor. As far as mounting points, I can easily get a baby pin to stick off of the track at multiple points via 1/4-20 to baby adapter, or cardellini. So there's that to grab on to.
Preferably, the setup would be afforable to buy, and small enough to breakdown into a large sedan. I also plan to shoot with it in the wilderness. I do realize sandbags may be a part of the equation.
Thanks!