# cat /opt/splunk/etc/system/local/web.conf
[settings]
root_endpoint = /splunk
tools.proxy.on = True
# cat /opt/splunk/etc/splunk-launch.conf | egrep BINDIP
SPLUNK_BINDIP=127.0.0.1
# cat /etc/httpd/conf.d/ssl.conf | grep splunk
ProxyPass /splunk http://127.0.0.1:8000/splunk
ProxyPassReverse /splunk http://127.0.0.1:8000/splunk
# cat /etc/httpd/conf.d/mysite.conf | grep Rewrite
RewriteEngine On
RewriteRule ^/splunk(.*)$
https://www.davidveuve.com/splunk$1 [R,NC]
The above is a conglomeration of a few different posts that I found. In essence, the apache mysite.conf sets up a redirect of anything from http to https. The ssl.conf sets up the Splunk reverse proxy. The splunk-launch.conf tells Splunk to listen only on 127.0.0.1 and the web.conf tells Splunk that a reverse proxy exists, and that it's going to be using /splunk/en-US instead of /en-US. (Obviously, I've changed my setup in a few other ways to protect the innocent.)
Hopefully this is helpful to someone.. in addition to myself, whenever I do this in the future.