Hello,
In you case, create a custom package with only Core Antivirus and Antispyware feature.
Check this Article for the same -
https://www.symantec.com/connect/articles/how-do-i-create-and-configure-custom-symantec-endpoint-protection-installation-package-vers
The Size of the total package would be 78.27 MB
Once the machine is installed with SEP client, it would require internet to download the antivirus definitions.
Regards,