I'd like to look at example 3 first. She did not go on a road trip. That's indisputably in the past. However, the main sentence concerns not the road trip the ridiculousness of not going. And the question you have to ask yourself when deciding between "is" and "was" (because they are both valuid English) is what you want to convey to those who will hear or read the sentence.
Do you want to convey that you're still outraged? Then it is ridiculous that she did not go. Do you want to convey that you were baffled when you first heard of her refusal? Then it was ridiculous that she did not go.
In the second example you can apply mostly the same argument. If the main point you want to get across concerns your feelings now, then it is crazy, while "was crazy" talks about your feelings on this matter in the past.
And again in example 1. Although in that particular case, I think it is much more common to use "was". But not for any English reasons, but more because it is common to tell the other person that the act of telling them the details made you happy back then.
Maybe a rephrasing can help you decide on a tense. Here we focus on your emotions as a speaker rather than "objective" characterisations of the events in question:
You told me the details, and it makes/made me happy.
He didn't attend school for a whole month, and that baffles/baffled me.
She didn't join her friends on the road trip, and that makes/made no sense to me.
Whatever tense you pick in these examples (and it doesn't have to be the same one each time), you should pick the same tense in your examples.