I pride myself on being pretty well up on Beatles lore but I didn't even know there were photos from the trip, which took place in October 1961.
This might make a good play. According to Lennon the fate of the Beatles was up in the air at this time, which of course would be the dramatic issue of the play.
There are two movies I know of made about the Beatles lives - both focused on John - 1991's The Hours and The Times which I haven't seen and is impossible to find, and 2009's Nowhere Boy which I just bought and about which I will have more to say later. And of course there Backbeat which focused more on the short-lived Stu Sutcliff. I own two signed posters of photos taken by his girlfriend Astrid Kircherr.
Apparently there was a reason for the bowlers - it was their belief that it was easier to get rides while hitch-hiking if you had a gimmick. According to McCartney:
We planned to hitchhike to Spain. I had done a spot of hitchhiking with George and we knew you had to have a gimmick; we had been turned down so often and we'd seen that guys that had a gimmick (like a Union Jack round them) had always got the lifts. So I said to John, 'Let's get a couple of bowler hats.' It was showbiz creeping in. We still had our leather jackets and drainpipes - we were too proud of them not to wear them, in case we met a girl; and if we did meet a girl, off would come the bowlers. But for lifts we would put the bowlers on. Two guys in bowler hats - a lorry would stop! Sense of Humour. This, and the train, is how we got to Paris.
Generally the only time this trip is mentioned is to note that this is when John and Paul had their hair cut in the first incarnation of the "Beatles" style by old Hamburg buddy Jürgen Vollmer.