you should make them a ship. maybe use the Mammoth W/ Ballista stats for it, and have a horde of red-goblins portaging it to explain it being on land. alternately, maybe just a Colossal giant carrying it on his back.
I have plenty of kunnin plans involving ships, mammoths and Giants. I just need to wait until 3ed drops as I don’t want to model a load of stuff and it not be useful. In the mean time I am just going to crank out infantry.