I'll post what I come up with if anyone is interested in, but I don't think it should be too hard to put together some creatures.
Actually, it's ridiculously easy to put together a new set of stats, be they creatures or NPCs.
I think the only trick at the moment is the lack of official examples to work from. The Beta book only had mynocks and young krayt dragons as creature examples.
I'm thinking creatures should just use the same rules as other organics regardless of size. If the captured rancor in the BegBox rulebook is anything to go by, you'd just beef up the Wound Threshold and melee damage for particularly big/powerful beasties.