I used DiskUtility+Bootcamp Wizard to setup my hard drive for Windows 8 (final MSDN). Somewhere in that process, the Apple tools turned my GPT disk into a hybrid MBR/GPT. All my 4 primary MBR partitions are used up, so when I try turning on Bitlocker in Windows 8, it complains about not finding a System drive. I know on Windows 8 the Bitlocker setup tries to create the 200(?)MB system partition if it's missing. However with all 4 partitions filled I suspect it can't create system drive => it can't find it => throws back an error like "BitLocker Setup could not find a target system drive. You may need to manually prepare your drive for BitLocker". I've already tried disabling hibernation, swap file etc. Now I'm thinking that if I were to get rid of the MBR scheme altogether, perhaps I can be alright within the GPT world without MBR's 4 primary partitions limit.

So, how can I get rid of the MBR tables on the hybrid scheme in a manner that still leaves Mac OS and Windows 8 in working conditions?

Details:

Hardware is the MacbookPro Retina. Primary MBR partitions are consumed as follows:

1. EFI partition
2. HFS+ partition (=encrypted, therefore ="Apple_CoreStorage")
3. HFS+ partition (Recovery partition, contains unencrypted Mac bootloader)
4. NTFS partition (Windows8 all-in-one partition)

diskutil list output

sid-mbpr:~ sid$ diskutil list
 /dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:          Apple_CoreStorage                         160.0 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
   4:       Microsoft Basic Data Win8                    90.1 GB    disk0s4

GPT vs MBR addresses

sid-mbpr:~ sid$ sudo gptsync /dev/rdisk0
Password:

Current GPT partition table:
 #      Start LBA      End LBA  Type
 1             40       409639  EFI System (FAT)
 2         409640    312909639  Unknown
 3      312909640    314179175  Mac OS X Boot
 4      314179584    490233855  Basic Data

Current MBR partition table:
 # A    Start LBA      End LBA  Type
 1              1       409639  ee  EFI Protective
 2         409640    312909639  ac  Apple RAID
 3      312909640    314179175  ab  Mac OS X Boot
 4 *    314179584    490233855  07  NTFS/HPFS

Status: GPT partition of type 'Unknown' found, will not touch this disk.**

**: Ignore this message, the gptsync tool is old and doesn't understand the UUID for "Apple_CoreStorage" / FileVault2 partitions. Since LBA addresses are alright, safe to ignore this message.