Thoughts on Ilari
What do you think of Ilari (Latin/Basque = cheerful)? Is it too similar to Hilary to be usable for a boy?
Depends on where you live. It's also similar to Ilia, but I'd say if you live in America/Canada/UK that it's probably too close to Hilary unless there's a large population of Basque people in the area.
It IS Hlary, just with a Basque inflection. Hilary was originally an exclusively male name. If you want to reclaim it, I think you might try changing the ending. Italian Ilario, Estonian Illar, Finnish Lari, Welsh Ilar and French Hilaire seem more masculine nowadays.
I would assume feminine upon reading, fwiw :)