Yeah I would love to have a dog that didn't mind being left behind, so I could do exercise and training one on one with each... but alas that will never be how Scout rolls. When it gets to the point where I can't take Lily upstairs to potty for 30 seconds (all pottying is on leash because my yard is only 3/4's fenced) without Scout ripping out of her kennel and destroy all the blinds in the living room... you come to the realization that some trauma can't be trained out and you need to make some concessions for your dog's issues rather than trying to make them "just deal with it."
Honestly if I hadn't had some dental issues come up I'd be a good way there for saving up for a third dog/pup. I don't want to take the plunge until I've got everything I need money wise laid away... it wouldn't be fair to my current animals or myself. In fact I was working on that when I took Scout in. That wasn't really planned (though after the fact I'm glad of course) and she is like a black hole for money compared to Lily, lol. A lot of people told me I was nuts for taking her in too.
But oh man, in a LOT of ways having a third would really ease my stress and make life easier!!