Encrypted DVDs beyond 2GB

[RW]

Some time ago I asked about creating encrypted data CDs, and someone suggested 
using mdconfig to create a file backed md device, encrypted with gdbe, and 
then burning the backing file to CD. 

That all works fine, but when the same technique is tried on DVDs, you run 
into the problem that FreeBSD 5.3 can't handle a file bigger that 2GB on an 
iso9660 filesystem. If you install the development version of mkisofs, it is 
possible to burn a DVD containing a file of up to 4GB. Windows 98 can read 
the file off the disk, but FreeBSD can't do anything with it.

Using 2 files and having the data mounted at two separate points would be a 
bit clumsy. Does anyone have  a better idea?