Hi.
It's important here to know available bandwidth between main site and remote site.
If bandwidth is limited then you need to setup Group Update Provider (GUP) on remote site.
New features and functionality in Symantec Endpoint Protection Release Update 5 (SEP RU 5) Group Update Provider (GUP)
http://www.symantec.com/business/support/index?page=content&id=TECH96417&locale=en_US
From the main server (RU7) deploy new package on all the 30 clients by selecting an option stated by Brian81.
Now those 30 clients will start communication with main site. Promote one of the remote site machine as a GUP to save bandwidth so that all the 30 clients will not come over the WAN link to take updates.
Available disk space on the remote site is the major issue so you cannot go with replication.