I maybe mentioned that I've been running Carrion Crown in GURPS. Well, I've had to make a racial template for mongrelfolk and as far as I could tell there weren't any other GURPS conversions that'd already been made. I decided that I would go ahead with making my own and then share it with everyone since I'm so nice like that. I tried to emulate the prolific Enraged Eggplant in presentation. I don't generally go with boxes or anything, though. I generally stick with humble messes of stats and lines.
Mongrelfolk have an interesting concept, and I think in a campaign down the line I may perhaps introduce them as a PC race in a fantasy campaign.
In addition to what I describe, they are generally a low-tech civilization, so it might be reasonable to assign them TL 1 or 2, perhaps even TL 0.
|The Mongrelman as envisioned by a Paizo artist|