I had thought along those lines but was curious to see whether anybody had tried this lens for wildlife. I posted my original request to see what a current user of that lens might have to say.
My idea is that even at 15 meters (45 feet) a 135 F/2.0 should be of use when the available light is very very low. Any image then seen at 100% in Lightroom should allow for cropping a decent sized usable portion. When I eventually decide to move to a D800 the huge 36MB images should be usable even moreso that with the ones I get from the D700.
For wildlife I always have a sturdy mono-pod with me too. As I said the 80-200 F/2.8D did not satisfy me and while I do think that the 70-200 VRII F/2.8 is probably better in rapidly diminishing light at the Equator, I am hoping that the 135 will be more useful for my specific need.
When I photographed polar bears from a tundra buggy in northern Manitoba I had a 300 F/2.8 and a Sigma 150-500mm that I had on loan (which I hardly used for a number of reasons). When I needed greater reach the 1.4 and 2.0 TC's with the 300mm were very useful. I have the TC2.0 III that has never let me down and which I assume will work with the 135.
On some occasions I have had to lug around over 20 kg (44lbs) of gear but there are instances in which all you want is - say - 3 or 4 kg (no more than 10lbs). The mono-pod can also be an excellent walking aid. Even a Lowepro waterproof camera bag can be too heavy at times.