Thanks so much, everyone, for your kind words of encouragement thus far!
I continue-on with what I though was going to be the hardest to get right - the mounting of all the cooling hardware. I don't have access to milling machines, lathes or fancy drill presses. All I use are electric hand-held tools, a hacksaw and a flat file.
I've used 4mm aluminium strip sheet to fabricate the bottom mounting plate, CCD tunnel as well as the top finger plate that presses against the peltier. The peltier sits on top of the finger and is clamped down snugly by the heatsink - which I've drilled and tapped so that the four screws from underneath can screw up through the set of plates and into the heatsink. The bottom plate has a countersunk (45 degree-bevelled) hole in it through which the CCD pokes. I've painted the whole plate matte black so that there is nowhere for stray light to bounce around in. The plate sits on the four threaded sleeves in the bottom case of the jiffy box.
With the 30w peltier running, the first test proved that the heatsink got very warm without the fan and stayed cooler with the fan running. The cold finger and CCD tunnel was VERY cold.... and without humidity in the air it remained dry. To the touch it filt like it was almost about to freeze. Yay!
I bought two peltier devices - one 30w and another rated at 60w. I'll do some experimentation in realistic conditions when I've finished this project to determine which I'll stay with. I can swap them over fairly quickly, so it's almost easy enough to do in the field.
Next - the wiring-up. I'll get that done over the next couple of days - stay tuned