Re-partitioning necessary/possible/how?

Hello all.

I would like to re-partition my GT-P7500 to create system partition of 1 or 2 GB size.
Reason for it - system partition is quite full even after full wipe and just necessary apps install. Especially since my migration on to Android 5.1.1 Lollipop (aosp-5.1.1-p4-20150729)

Is flashing with Odin + customized pit file the only way to do it?
Who could create pit file with, let's say 2GB system partition?

I really don't mind having smaller data area, but want to avoid space issues in system.

My partitions now, after full wipe/basic install:
Cache:
total - 440.95MB
used - 7.5MB
Efs:
total - 11.80MB
used - 8.14MB
Data:
total - 12715.62MB
used - 1862.17MB
System:
total - 568.89MB
used - 490.57MB (86% !!!)

Thank you and have a nice day.