Heh, yeah. I feel your need to experiment, but like i said: I concluded>nothing useful about putting that much crap behind a 1000mm lens
and immediately forgot why I even concluded that.
Your image probably sums it up nicely though.
Mind you, my teleconverters are all disgustingly dirty, so that and the general optical degradation associated with any tc really didnt help.
The 1000mm has a minimum focus of 8m, iirc, so if I was to get serious about putting all that junk behind *any* lens it would have to be one of the better 500's I have with a 1.8m minimum focus like the 55BB. Which is actually the lens I used to use specifically to shoot things in pseudo-macro at my feet, while on my daily walkabout.