When I read "cucumber sandwich" I thought you meant those dainty little crustless bread sandwiches with sliced cucumber inside that they serve with a classic English tea.
It's novel using the cucumber itself as a container for the filling. I feel like you should have added back the inside of the cucumber that you had scooped out, to make another layer, as it tastes nice.
Oh, my goodness, you people are going to make me go to the market today after all. LOL! I like to make a cucumber/dill/yogurt dressing to add to those dainty little sandwiches.
I did eat the insides, but I think to add them back to the sandwich would make it rather sloppy. If you give it a try, let me know how it works. I'm certainly not for wasting it! Thanks for the input.