I'm in the same boat as you Tracy (Border Collie/German Shepherd mutt), though I live in an apartment in Toronto. Truth be told, the only thing you can do is make it your mission to kill them in the morning (not literally of course), and then make sure they are occupied during the day. The only way I can do this for my pup, is to wake up with enough time for an hour and a half walk. We start off the walk with a 10-20 minute training session whereby we work on whatever it is I feel like working on for the day, followed by a hike of sorts around the city for 30 minutes, with him heeling for the majority of it/being treated for walking properly. This exhausts him. I then end up at a park with some other owners, where he plays fetch/plays with the other dogs until we go in.
He then gets walked again by someone I pay daily around 11-12, and, of course, gets another hour or so when I return at 6ish. All in all, it's about 4 hours of walking/stimulation outside, and he's still raring to play when we get inside etc.
The fact of the matter is, these guys were built to do a lot more than we can throw at them, especially physically. All you can do is tire them out to the point where they nap a bit before wanting to play again