Update on the garden challenge

Last week, in my blog The next training challenge, I wrote of how I’ll be attempting to train my dog to not use the garden as his personal toilet.
I later wrote Catch'em in the act, which details how to stop the unwanted behaviors that your dog engages in when you’re not around.
The two blogs are linked, and here’s how:
Do you think I go outside with my dog every time nature calls?
No way.
So, in order to train him to stay out of the garden, I’m going to have to repeatedly set him up.
Training him not to go in the garden while I’m around is a piece of cake. I just tell him no and ask him to come whenever I see him put a paw in the dirt. Eventually, he learns the garden is off limits ... while I’m around.
Training him that the garden is off limits when I’m not around is the tricky part.
Fortunately, I think it’ll be a lot easier to set him up with this one than with the garbage can, which I described in Catch'em in the act.
This is because the garden runs along the front of the house, and there are windows above it.
All I have to do is set him off on the chain to do his business, then follow him from one window to the next without him catching sight of me.
Every time he heads for the garden, I need to be ready to open the window and shout, “No! Bad dog!”
The downside is, I will have to do this every time he goes outside — no exceptions — until I visibly see him being successful in going out by himself and not going in the garden.
And not once, or twice, but several incidents of success will have to occur before I believe my job is done.
Would you spend the time to do this?