Maybe a bit late as OP probably have made the trip by now. But still, lashing on ferries are important to know. I frown on the "over saddle" method as it requires so hard lashing over the bike that you're certain the suspension is well compressed. With a risk of the saddle to tear or break. If not being lashed down hard this way, the bike is likely to shift and move if rough sea is encountered as the bike's suspension compress and release due to the vessel/ferry movements at sea.

But to an ADV bike that normally has protruding pillion foot rest hangers and even solid crash bars, three anchoring lashes are required. I'd like to lash down the bike myself in this way:
1) Put the bike on the side stand.
2) Engage 1st gear.
3) One lashing from the left pillion foot rest hanger diagonally forward, out from the bike to forward lashing point in ships cargo deck. Lashing length need max to be +1m / 3-5'
4) One lashing from the left pillion foot rest hanger diagonally rearward, out from the bike to rearward lashing point in ships cargo deck. Lashing length need max to be +1m / 3-5'
5) One lashing from the right pillion foot rest hanger lateral out from the bike's right hand side - preferably perpendicular to the bike, to lashing point in ships cargo deck. Lashing length need max to be +1m / 3-5'
6) For additional peace of mind, strap the front brake lever to the throttle handle by means of a small adjustable strap as a "parking brake".

Done this way, your bike is secured to forward, rearward, lateral and up/down movement. It can also be lashed down way harder than usually is achieved by the single lashing over the saddle.
Have a safe trip and enjoy the ride!

... where did you find the Tiger schematics?

the aux lights don’t remain on after toggling from high to low beam

- The T-plane crank makes the TT1200 PV01 vibrate. Letdown after owning a turbine smooth 2012 Tiger 800 triple. Triumph claims it to be "character" though. I don't approve.