While it won't work with the Paizo-only restriction, I just want to let you all know that your fellow myth weaver made a Mongrelfolk race specifically for this game and it was published on D20PFSRD: https://www.d20pfsrd.com/races/3rd-party-races/ozzykp/mongrelfolk-12-rp/
Of course, even if non-Paizo sources were allowed it wouldn't quite fit in the campaign for a mongrelfolk character to start the game topside with the rest of the characters, but maybe something to keep an eye on in case there were an opportunity to use it in the future for PCs or NPCs.