Can anyone explain how the Trim/Trailer switch should be used in comparison to the Trim UP and Down switch? Will the Trim/Trailer switch only operate at a certain drive height?

The trim button raises the drive until the trim limit switch opens the circuit. This prevents you from over trimming on the water and damaging the u- joints. The trailer switch is used to raise drive all the way up,past the limit switch, for trailering. There is a specification for limit switch adjustment in service manual.

Anybody here use the trailer "out" switch (in very short bursts) to bring/move BOTH drives up/out together when running at speed?
I am having a challenging time hitting both Bravo drive unit trim switches precisely together.

My pumps run at different speeds with the starboard lagging behind port by a couple of degrees… using trailer out switch doesn’t cut it on mine.

Do some digging and you’ll find that you can adapt switches to work on your throttle handles. That may be a solution.

I also have a CRT helm that has trim switches built into the steering wheel spokes. I have not added it yet because I would need to get a shorter steering shaft make it fit with my bolster.

Lots of options.

Thanks, I've been reviewing but so far it has not been critical...
I hope you are enjoying your new beast motors!