I flew from NY to Germany twice in my days. Once on United and the other on Singapore Airlines. Both are very comfortable but, my suggestion is to get enough funding for, at a minimum, business class seating. Definitely a requirement for clearing your mind prior to initiating a huge half thought out plan or if you are interested in watching a few movies for 10 hours.
Good luck 
Regards 
Ah, yes. Paying a random person for business class cross-Atlantic travel… even better…
The “doers” and shakers of the world don’t need to crowd-fund a plane ticket!
Fun fact, Hamburg has more bridges than any other city in Europe.
Plenty of sleeping opportunities.
Last time I went to Hamburg, I worked for a large oil company slap bang next to the red light district - plenty of sleeping opportunities there! 
Have been to Hamburg a handful of times, most memorable was a Al Di Meola concert.
Sleeping in an abandoned house in an scrap yard afterwards.
About 6 in the morning it started raining heavily and lightning did strike the house, almost ripping a radiator of the wall.
That trip I will never forget.
What’s the ratio of bridges to trolls? I’m sure there are a few that don’t have one, plenty of opportunity there.
He may, however, need to settle on an obscure bridge in a suburban neighborhood. I’ll bet the good ones are already taken.
I’ll pay his Uber to the airport (but Uber X, please. I’m not that rich).
