Upload & Sell: Off
Well, seems like there's only one lens that can take the 3x TC without any noticeable loss of quality, my MP-E 65mm macro, which gives it 3x - 15x magnification. Though at that magnification, the bloody diffraction sets in early.
I'll give that 1.4x a try, but what about two 1.4x TC? that'll be pretty close to 3x. I'll need a LOT of light for sure but hey, if there's one thing Australia is not lacking of it's the sun.