I would suggest to use AutoYast :
1- Try to reproduce what you have done in order to get the actual configuration, that means try to write a script that will describe what you have done to get the actual configuration.
2- Get a bootable ISO installation media for SLES 15
3- Create your xml Kickstart configuration file, you will need to specify :
Packages that need to be installed.
pre script section to execute before the installation.
post script section to execute once the installation done, here you can use the script you wrote in the step 1
4- Use jing parser to validate the kickstart file.
5- Bundle the installation media with the kickstart file, it depends on the environment :
Use a PXE server to make a network installation possible.
Or, use a media device, like cdrom or flash usb.
Or, if it's a virtualized environment, just mount it on the targeted
VM and then change the grub/uefi entry to use the kickstart file
with : inst.ks attribute.
6- Test first this procedure on a test server then deploy on the other nodes.
Here is the full documentation you will need to implement this solution AutoYast Doc