This is what I am using so far as Tau proxy ships.
The Mecha ship is from Space Battleship Yamato, I think. I saw the dimensions on Amazon, but I think that those numbers describe the box that it comes in, for shipping purposes. But I did find a review of this one that listed it as 'between 4 and 5 inches', so that put its at 10-13cm. That's not bad, but my current Cruiser-equivalent minis are about 9cm long each, so it might not look big enough compared to them..... but that's something about the mini itself so I might pick one up just to check it out. I am sure I can find a use for it later even if I don't use it here.
The Dropfleet Destroyers are a bit small I think, but I will keep them in mind for the light cruiser ships of the Tau fleet later. I did ask some DFC players here and apparently Resistance Trident Battleship is around 15cm, depending on how you build it as there are a few options in the build. This might be a little big..... but I really like it, so I might just use it anyway. The rule of cool!
I will keep looking around, but right now I will probably pick up the Mecha ship that I like and the DFC Trident Battleship you suggested and see how they feel in hand with the rest of my growing fleet.
