I had something similar, techsmith relay.
What I did was copy both files to a sub folder under temp. Then use a script to execute the installation. When I get a chance I can post my relay info.
My Notes
Copy contents to /tmp
Add to composer
Export as dmg
Upload via jamf admin
You must capture the original pkg file & the config file.
When the pkg file runs, it reads the settings from the .plist file.
Installation
• Distribute via policy
• Run Install Script
Install Script
#!/bin/zsh
installer -pkg /tmp/yourinstaller.pkg -target /
exit 0