There are a dozen apps in apps.splunk.com for F5. At least one (https://splunkbase.splunk.com/app/3161/) supports version 13.x.
Cheers Rich
Many thanks for you answer Rich but I meant to say 13.1.x as I can only find tested solutions for 13.0.x.
Any ideas?
Some ideas.
1. Contact the developer of the 13.0.x version to see if it will work or if he's working on an update.
2. Download the 13.0.x version and examine it to see if it will work with 13.1.x.
3. Install the 13.0.x version on your dev system and see if it works.