IMO...
As a TFPer, if I were your neighbor, I would insist on taking care of your pool while you're away. No big deal. But if I was your neighbor that had already offered to look after your house, and I was paying someone to maintain my pool, I would resent you for asking me to also take care of your pool, for free. I don't see that as an option. You shouldn't even ask.
And I would not drain that pool. That'll just risk ruining the finish.
So either let it go green, or pony up and pay a maintenance company. I would start with the one your neighbor is using, see if they'll offer you a military discount, since they'll be in the neighborhood anyway. Based on your worry of one or more pieces of equipment breaking down, you need a pro to look after all that, along with the water chemistry. Asking your neighbor to test and dose the water would be bad, but sticking him with replacing a pump or SWG would be really, really bad.
I agree that the analogy of a broken toilet doesn't apply. It's more like turning off your irrigation system because you don't want to pay for water or fertilizer or a gardener, and letting your garden turn brown and overgrown. Maybe it'll come back when you get home, or maybe it'll be completely dead, or somewhere in between. The expense of revitalizing the garden would likely be more than the cost of the water. Recovering a nasty pool could be more than the cost of maintenance, when you consider the chemicals plus your time.
The reality is, pool ownership is expensive, and that expense exists whether you swim in it or not, whether you are home or not. The cost of maintenance has almost nothing to do with the use it gets. Like if you were home and broke a leg and were in a cast, you wouldn't let your pool go. You'd take care of it until you could swim again. You're looking in the wrong place to save money while you're away. About the only thing I could suggest is that you swap out that pump for a variable speed pump now, before you go. Even if the existing single speed lasted another five years, a VS could pay for itself before then in energy savings. (There's math you can do to see if that's true.) Then keep the old pump as a backup.
The reality is: it costs money to make money. Your job takes you away from home. Part of the expense of the profession you've chosen is sometimes paying to have your pool cared for. Just like someone that chooses to work 30 minutes from home must pay for gas to get there. Or like a business man that must pay for his suits. Basically, your pool maintenance expense is the cost of doing business. I think you gotta pony up for the pool, and then you won't have to worry about it, and it won't be a nightmare chore on your return.
Flip the script: don't think of the pool maintenance cost while you're away as an unnecessary expense, think of the money you save by doing the maintenance yourself while you're home.
