Yes...yes...by all means add perilite to your soil !
20 to 30% sounds reasonable and what I use..
FF has a nasty tendency to clump after a couple of months of use..leading to some nasty spots deep down.
However mixing in perilite helps to alleviate this problem...allowing more air to the roots, prevents dead spots and mix burn. Also makes flushing easier...you may need to water more often but man it is worth it !
Do it....quit reading this post and do it !
Also give yourself a 2 to 3 inch ( 4 would be better ) base of small rock, broken pottery ..those balls they use in hydro...mixture of all 3 would be best or whatever you can find ( well washed of course).... for the bottom of the pot to help with water flow.
Also I keep my pot about 4 to 5 inches above the drainage saucer...which allows airflow through that area...but that's a personal preference. I also doubled the drainage holes...