After a lot of trial and error I figured out the solution to my problem. My publisher rules file looks like the following now:
<?xml version="1.0" encoding="UTF-8"?>
<rules xmlns="http://www.ptc.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ptc.com PublishRulesSchema.xsd" evaluate-rules-on-republish="true">
<authoring-application name="PROE">
<additional-files name="drawing_files">
<!--only default='true' files will be generated at this time -->
<file display-label="PDF" type="pdf" default="true" output-prefix="pdf" />
<file display-label="DXF" type="dxf" default="false" output-prefix="dxf" />
</additional-files>
<additional-files name="part_files">
<!--only default='true' files will be generated at this time -->
<file display-label="STEP" type="step" default="true" output-prefix="step" />
<file display-label="IGES" type="iges" default="false" output-prefix="iges" />
</additional-files>
<additional-files name="asm_files">
<!--only default='true' files will be generated at this time -->
<file display-label="STEP" type="step" default="false" output-prefix="step" />
<file display-label="IGES" type="iges" default="false" output-prefix="iges" />
</additional-files>
<condition name="is_drawing">
<attribute name="epmdoc_name" regex=".*\.drw" />
</condition>
<condition name="is_part">
<attribute name="epmdoc_name" regex=".*\.prt" />
</condition>
<condition name="is_asm">
<attribute name="epmdoc_name" regex=".*\.asm" />
</condition>
<!-- Following conditions are evaluated based on the order they appear in this file -->
<if condition="is_drawing">
<publish on="checkin" display-label="Publish drawing - checkin" additional-files="drawing_files" />
<publish on="create-representation" display-label="Publish drawing" additional-files="drawing_files" />
</if>
<if condition="is_part">
<publish on="checkin" display-label="Publish part - checkin" additional-files="part_files" />
<publish on="create-representation" display-label="Publish part" additional-files="part_files" />
</if>
<if condition="is_asm">
<publish on="checkin" display-label="Publish assembly - checkin" additional-files="asm_files" />
<publish on="create-representation" display-label="Publish assembly" additional-files="asm_files" />
</if>
</authoring-application>
</rules>