I think you're on the right track! There's not a right or wrong answer here, you have to do what works for you.

It might be helpful to not really consider this one message you want to give them, but two. Message one is "I have a crush on you", and it's the undeniable, emotional one. Message two is "I want to do something with the crush" which is the one that you're still deciding what you want, and really needs their input on what they want. You're not going to decide to get rid of the crush, the rest you can decide not to do even if it will hurt to give up on it.