Glad I'm not the only one with this crazy idea! I have to say that telling him only a few hours before you leave is AWESOME! Guys really don't need much notice. Give me a bar of soap and a toothbrush and I could pretty much go anywhere for a week. On the other hand, I think my wife would totally freak out if I only gave her a few hours notice.
I totally hear you on the "saving for years" thing. We're both involved in the finances so it's kinda hard to hide $5k. I've been slowly stashing away $ a little at a time.
So excited for you! Hope your reveal goes exactly as planned!