Export KOHA_CONF and PERL5LIB path while running sip_run.sh script (Change installer to give the automatic path of KOHA_CONF and PERL5LIB)
This will make it possible to create a service for SIP using sip_run.sh.
I don't think hard-coding those values into a shell script would make sense. Typically, one should use the Debian packages. If not using the Debian packages, then creating a service file where hard-coded values could be added might make sense (unless it's systemd which has nice template options)