they should fit just fine on 25GB or larger BD-R. What exactly are you running into issues with?
(Also, this should probably go in the How-To section of the site, where there are some topics that might have answers for you)
such as:
http://originaltrilogy.com/topic/Burning-the-Despecialized-to-Blu-Ray/id/46433
JEDIT: and Merry Christmas to you too!