Hey,
I live in an apartment (so no backyard
), but I rarely work more than a few hours a day outside my apt, so I don't have those issues, but I guess I would recommend piddle pads for sure. That seems like too long to make them wait. I don't have a whole lot of suggestions about being gone for 8 hours, but I'm sure others will.....
Good luck with your puppy (and post some pics when you get him/her)