Hey, Tyler -
http://www.infopathdev.com/blogs/hilary/archive/2013/01/17/qrules-submittosharepointlist-and-a-person-or-group-column-type.aspx has the syntax that we need to submit. We usually add a field to the schema and use a double eval to concat the person or group info from the form with the "-1".
Here's a sample default value:
substring(xdMath:Eval(xdMath:Eval(../pc:Person/pc:AccountId[. != ""], 'concat(";-1;#", .)'), ".."), 2)
In this case, the field with the default value is at the same level as the pc:Person group. Then we map the field w/ this default to SharePoint.