Just wanted to share a proto that I might be using pretty soon. It's far from being awesomely portable (actually, unless it's mounted on the back of a pick-up truck, it's not transportable), however it should have quite good precision.
I need to unmount the mirror and then mount a camera mount, which shouldn't be too hard, considering there's roughly 30 engineering teachers and 1000 students ready for action, so I just need to sell the idea to a group and wait for the result.
Here are some pictures of the actual rig.
The advantage of the above is that the software already exists to do solar tracking. It wasn't very dynamic (trajectory has to be pre-programmed, minor adjustments based on another system possible), but I'm free to use any software I want for controlling it. If possible, I'll definitely try to get this project's software to run on it. Also, if I get good results, I'll post some hardware spec. At the moment, the rig (including mirror) weighs something like 35kg (hence the limited transportability), and requires full AC power. The mirror itself weighs in at around 15kg (so the mount is strong enough for most hardware I'll be able to throw at it, currently my biggest lens is a (borrowed) canon 200mm L f/2, around 2.5kg)
The following is what is basically a very small dolly. Probably useless, considering the minimum step is roughly 1cm, it's very jittery and has only a span of about 10 ft.
So, anyone else planning on revisiting their schools to try and recycle some gear?