I can totally understand where you're coming from, as I've endured this problem myself! Even though you're sure this problem is behavioral, an evaluation by the vet and analysis of a fecal sample would be a good idea at this time, just to be sure there's no underlying medical problem causing her inappropriate defecation. If a cat experiences pain upon urination or defecation, she will come to associate the PLACE of eliminating--the litterbox itself--with that pain, and then choose to eliminate ANYWHERE else, so it's important to keep that in mind.
In order to prevent your cat from returning to the places she's already soiled (if she smells it, she'll keep thinking they are appropriate toileting places), you should use an enzymatic cleaner to completely remove all traces of stain and odor. Nature's Miracle and Zero Odor are good products for this purpose, and can be found in Petsmart/Petco, most pet supply stores, and online. For more info and to view all related products, please see:
If you're correct, and due to your work hours and the dog, she's stressed or anxious, Feliway, a cat appeasing pheromone which can help to calm stressed cats and curb inappropriate elimination, should help the situation. It comes in both a spray and plug-in diffuser. The diffuser plugs into an electrical outlet like an air freshener, but has no scent to humans.
For more information, please see:
Major pet supply stores like Petco/Petsmart carry Feliway, you can also order it online, and some vet offices carry it.
There's another product which I think may help you get your kitty back to using the litterbox all the time--it's a clumping kitty litter called 'Cat Attract'--it contains herbal attractants which encourage use of the litterbox. It too, may be found in major pet supply stores.
You should have more than one litterbox, if you don't, already. Some cats prefer to urinate in one box and defecate in another. The rule of thumb is usually one box per cat, plus one. If you have a multi-story house, a box on each level is also appropriate and usually prevents accidents. Of course, keep all boxes immaculately clean at all times, and I'd try to clean her box out more than twice a week, as this may help, in part, to alleviate the problem.
I hope all goes well, my suggestions prove helpful, and this problem is resolved very soon; good luck!