What is safe to exclude when doing a UFS backup?

We are running a tiny (< 1GB) Pg installation, but are starting to
migrate over our production Oracle apps.

We run a daily Oracle dump and a daily Pg dump to /var/tmp, keeping the
most recent four versions of each.

Nightly, we have Veritas Netbackup backup the whole filesystem to a tape
library.

Currently, the Oracle data directory (which also has the redo logs) is
excluded from the UFS backup as those datafiles are 100 GB and are
completely useless in a restore.

I have not excluded the Pg data files since I don't know what is safe to
exclude and the files are very small.

As we migrate apps and the Pg install grows, we will need to exclude
those data files.

Which directories/files are safe to exclude from the UFS backup?  In
other words, what files can Pg live without and still get off the ground
far enough to restore from a pg_dump?

Thanks in advance,
Marty