I really like the idea of cucumber. My only concern would be the flavor not being prevalent enough to be as noticeable as you are looking for.
If I might offer a suggestion, I would recommend the infusion route that was previously mentioned. Basically a "cucumber tea", but upping the second part of the equation by using an actual cucumber green tea. I make a cucumber iced tea that picks up a lot of the cucumber flavor.
Basically, make a batch of green tea like you would prepare for iced tea. Allow it to cool completely, then add a lot of sliced cucumber. I leave the skin on, but I doubt it makes much of a difference either way. After about two days in the fridge, the cucumber notes really start to come through.
I've actually mixed this with Duvel, about three parts beer to one part tea, and it is a very nice flavor profile that it adds. If you go any sort of infusion route, you can always make the infusion, pick up a few brews that match what you are targeting and do some mixing to get a relative idea of the quantities and ratios you might need.
I am sure that it isn't a flavor for everyone, but it really has a "spring" quality to it that would make for a nice seasonal.