How do I upgrade laptops to Sep 12.1.6 MP4 that are off the company network?

I am currently rolling out the new 12.1.6 RU6 MP4 to my company desktops via install packages.  However, our laptops are constantly offline due to travels so i would like to know how we can deploy this update to them? I can schedule the same way as the desktop but the package is 735mb.  I cant guarentee the laptops will stay on vpn that long to download it. What if they dont check in with the vpn? Anyway I can schedule it to pull from Symantec directly?

Thanks