How to Trim Your Mainsail on a Catamaran

[Catsoon]

OK Folks- I need some help. I was a monomaraner, and two years ago bought a 1995 FP Athena and brought her here to the SF Bay. I am struggling with how to properly and effectively trim the mainsail. Given the width of the boat, the fact it doesn't heel, doesn't have a boom vang, and has a 20 foot traveller (that's not easily moveable)- I don't think I am optimizing the trim. A few questions:

what visual things should I have installed on the mainsail to assist in trim? Stripes, TellTales, anything else?

what are your main trim mechanisms? Mainsheet vs. Traveller?
What are the right traveller settings? How much does Boom height matter?

It seems like such a basic question- but I'm not getting it yet and would love your opinions? If you want to point me to some good articles or books, I am great with that too!

Thanks! CHRIS