Yes, Registering the pkg through the Post Office is the most secured way. (No need to insure it when you register it.)
Every time someone handles the pkg, they must sign a in house Postal Record. When mailing, You must declare a value,( just make sure you can prove the value, either by different books etc.) and the value declares the price it cost you to mail.The pkg goes into a locked pouch and is recorded. When the driver picks up this pouch, he has to sign for it and so on down the line. You can also track this on line. Now the time frame can take up to 10 days, due to security. The % of something going wrong with this is less than 99.99999999999 %
Hope this shed some light for you.