Is there a way to take space from the /opt slice (/dev/dsk/c1t0d0s5) and then put it in the /var (/dev/dsk/c1t0d0s1)? In theory, I should be able to ufsdump /opt and /var to another drive. Use disk label to resize those two slices (ex. take 10G from opt and add to /var) and then newfs and dump back over. Correct?
Yes, but you'll need to do that from single user / failsafe / boot from CD mode, i.e. a mode where /var and /opt can be left unmounted.