Don't get me wrong, I love this kind of "get it done" policy, but it's not vacation if you work "a couple hours a day". Vacation is when you are able to really forget about work for a while.
That being said, I fully agree about the impossibly short warning time he's advocating. Six months sounds more like it.
I get that; that's why we define a "vacation" by the amount of time one of my guys is going dark. If you're going dark for two weeks, that's a vacation. If you're going to be scuba diving and only checking emails nightly, that's just reduced production capacity...just let me know so I can plan for it and please don't do it right before a deadline. :)
IMO this issue is indicative of the relationship between employee/employer. The tone of the OP is so "eff you, I'm outta here" that the relationship must already be dysfunctional; there's a lack of trust and respect and that's ultimately the employer's responsibility. Something is wrong with the company's culture.
I don't remember a vacation where I didn't "work" - willingly. I usually get bored and get the itch to write some code. I guess that happens when your work is the same as your hobby.
That being said, I fully agree about the impossibly short warning time he's advocating. Six months sounds more like it.