This is what I would do - come home at 3:30, do stuff with the dog, tire him out, go out and do errands. When I got my first dog, I read How to Be Your Dog's Best Friend - I don't even know if it's a good book anymore, but I remember it saying how now your schedule revolves around the dog. On days it's not possible, get a really good person to help you out.
Yep, keep doing that - I talk to the dog about what I want - hey, let's poop out here, kind of thing. They really are confused - when they are in a smaller area, they don't want to mess it, like in your bedroom - or if they don't NEED to do it and can hold it - but smart dogs will poop in the house if they need to go and don't know how to ask, have enough room to do it, etc. Using bells on the door to help him tell you helps too.
I do a potty schedule, and the dogs seem to respond well to that - but it's great for them to be able to come get you when they have to go, and that will come with time. I have an 11.5 yo GSD who is still weird about telling me - she will stare and walk, but is not pushy enough to nudge or paw. Every once in a while at night, she will stare and walk, and I am sleeping, and she's like, well, guess I just need to go....noooooooo!
But now, my BC/Chow mix is getting me for her!!! I have a
service dog! YAY!