TLDR: Seems to work ok. Haven't run into any problems so far
DPA running http on 8125. Apache httpd 2.2 running on 443. Added ProxyPass /iwc http://localhost:8125/iwc to httpd.conf file. Also had to change om.confio.iwc.emailLinks.urlOverride= in my .../iwc/tomcat/ignite_config/idc/system.properties file (as per instructions on "DPA email overrides" at Success Center ). to just be https://mymonitor.mydomain.com/iwc so clicking on email links work.
Now can use various Apache httpd modules and directives (ie: CustomLog, Allow from) to better control what's what, rather than fussing directly with tomcat xml files.
Caveat, probably not *officially* supported, so as always: ymmv.