URGENT-No Exchange Backups to Tape

[Gasp100]

Ok guys, I need some guidance here. This is my current backup policy with some additional configuration because of our infrastructure.
Official Retention Policy:
All backups DAILY 3 months on disk
All backups WEEKLY 6 months on tape
I expressed in another email that I have moved about 75% of my VEEAM backup infrastructure from a Data Domain in PROD to a Windows Server + NexSAN as my new repository.
We have tried to CAREFULLY make sure that each weekend VEEAM looks at any repository with FULL BACKUPS and clones them to tape.
Now, I have been reading so much about how great synthetic fulls are and incremental forever, never really needed a true "full" so I went ahead and implemented that for my Exchange DAG group. My thinking is now that I'm done doing a ton of changes (mailbox moves, seeding 400+GB databases, etc...) Exchange and VEEAM will finally calm down and I can stop worrying about backups... just let VEEAM do it's thing (quickly), truncate those transaction logs and go along it's way.
Well looks like because I'm not doing an active full or a real full for Exchange my backup to tape job is SKIPPING ALL OF EXCHANGE.
This is a huge issue for us because we have many users on litigation hold and we need to retain Exchange backups offsite indefinitely.
Can anyone offer the BEST configuration for me???
I'm thinking incremental, let VEEAM use internal Deduplication to the NexSAN and I have it set to every 8 hours.
Should I even consider synthetic fulls in my current situation? With Microsoft DPM we basically did "incremental" which applied / truncated logs every 4 hours and then what is called an "express full" once a night. But with DPM tape cloning an "express full" IS considered a real full so it would always clone as well.
I need the SAME functionality out of VEEAM.
Should I go back to INCREMENTAL every 8 hours, skip synthetic fulls and just do active or real fulls on Saturday?
Right now we are talking about 4TB and once I get the rest of Exchange DAG out of DPM we'd be closer to 8TB total disk (more like 5TB total data).
PLEASE HELP me understand the best way to balance this?
I do understand I could try and tweak the tape backup job but if I introduce incremental backups it looks like it will search for ALL incremental which I don't need.
I guess I could create a special second tape job for Exchange, but then I'm concerned about interleaving the tape library.
I noticed there is a hidden setting in the tape job but I don't know if this can grab a synthetic full and clone to tape???
"Specify virtual full backup schedule for source backup jobs which use a backup mode without periodic full backups" -- I have this set to weekly on selected days (Saturday, Sunday) and Saturday is when my Exchange job does synthetic full. I thought this would grab Exchange but no?

[foggy]

It would be great if you could describe how your backup and tape jobs are set up in more detail, so we could get a better idea of what actually happens. Thanks.