Bergen’s and rucksacks are great if you have to haul a load on your back but not great for vehicles and vessels, too many straps and bits to snag. Coach companies and airlines hate them.
For this sort of trip I’d go for a hold-all. Easy to shove under a bunk, you can also open the top and see what’s inside without unpacking everything as with a rucksack.
I have a mesh bag for separating dirty washing and a small pencil case/wash bag for charging leads, spare batteries etc.
My laptop, camera, binos and any other tech would go in a daysack. The daysack can then be used on excursions.
I have a mountain warehouse copy of the north face duffel. It’s 60ltrs and has detachable shoulder straps for a short yomp if needed. It was £40 on Amazon