Try a model action. You can set up an action that is triggered by one field changing that updates a different field. You could also try creating a formula field in Salesforce, or a UI only field in Skuid that would use logic to pick an answer based on the selection from the pick list.

I love Raymond’s ideas.  In the worse possible case you can use our Javascript API to build a snippet that updates the second field.  The snippet would get triggered in a model action on update of field 1.  This way you could add conditionality (If field 1 = Foo,  field 2 = Bar, else Field 2 = Nothing)