Cucumber would be fine and a good idea
When we took our hammy in the car I sat with the pet carrier on my knee, holding onto it, with a blanket over the top so flashes of sunlight etc and cars didn't bother him. I would put as much bedding as you can in and maybe hide some treats or bits of food in the bedding which should occupy him. A small house could be good rather than a tube maybe (ie small cardboard box with a hole cut in?). Our hammy goes in the little house and builds a nest in there when he's in his pet carrier, and I think they feel a bit safer in a house. But it depends how big or small your pet carrier is I guess.
Or something like this - normally that would be a bit small for a Syrian but if it's on top of substrate/bedding it'd be fine. Or a little hide from your cage or something
Amazon.com : Kaytee Itty Bitty Mouse Igloo Hideout, Colors Vary : Pet Habitat Decor : Pet Supplies
Exciting! Looking forward to meeting your new hammy