Hey, sorry for being 'away' :)
Hmm, I don't seem to get that error, and your calling line looks ok. I wonder if that was just some temp issue or if it still exists for you.
For this one I didn't include any simple ways to modify outfit, but you could do it in "spawnGroup.sqf" I think. Probably after line 60 would be good spot to maybe call outfit script which adjusts unit's gear depending on their side etc.
Let me know if you feel like trying or need assistance with it.