I'm curious about the .5 month window for informing employer. I assume this is because you would quit the job and 2 weeks notice is customary. Perhaps for some though a much longer window might be required to arrange a leave of absence/sabbatical. I know with my union I am allowed one extended LOA every 5 years or so and still have my position available upon return.

As it is I am doing a one month tour this fall (smaller than the example I know) and one of the first things I did, after determining I could do what I wanted in the allotted time, was to approach my employer to ensure I could take all my vacation time in one shot (so they could arrange adequate coverage). That was probably the one big hurdle to overcome before I shifted from maybe to actually going.