The tilt bracket on the motor is for mooring use only, so you can retract the rams to protect them from corrosion.
You also don't want to raise the engine so high, it will tend to bounce up and down as you hit bumps since the weight is more balanced and not biased more so to push down. On smaller boats like bass boats there is a concern with torque stress on the short transom with the big 60 mph motors.
I see no problem towing the boat with the engine tilted but no more than needed, so the two trim rams are in contact (trim range) at all times. And just high enough to clear any issues with ground contact.
I was in a Subaru dealership looking at a new model over the weekend, I knew more about the model specifics than the salesman did, after spending just 1/2 hour on the factory website before the visit.
Of course, unlike me, salesmen can be very good at acting like they know when they don't, and what would most people know any way?
If there are any missingblanks, they make it up as they go.
Ignorance is bliss. Me, I'm cursed.
I give each saleman a test when I first meet, ask a question I already know the answer, to see what I'm dealing with, no surprise results I can tell you.
If you are cursed like me, read the owners manual yourself. I don'th think they trust salesmen to author it.