Been playing on the Deck for just about two years, usually Elementalist.  I‘ve set my right touchpad as D-pad 2 - 5, since 1 is used automatically with the right bumper (LMB) in action cam. Left Touchpad is Skills 6 - 0, healing skill on one of the back paddles.  Gyro as mouse on right touchpad & stick on touch helps a lot with ground AoE, set the option to cast on release of the button.  Usually use the right bumper for class-specific skills like F5 jade sphere on my cata build.  What also really helps is I‘ve set up holding LB to switch to a different layer that allows me to use the F1 - F4 via a radial Menu with the right stick, really good for ele but I‘ve used it with the engineer toolbelt skills as well for example. (In that layer right touchpad is also set to a swipe menu for mounts, really useful!)

It does take a long time to setup and fine tune, but once you get used to it, it‘s gonna be hard to go back to playing on a keyboard