Toby has got an infection on the right side of his throat, one that may have its root from a long way back. It has been surgically removed by now, but he also has some cancerous growths in his lungs. His prospects are therefore not very good. I shouldn't complain, because he is old by now considering his size and breed. But still, it lasts heavely on me.
The way you described the circumstances you and Haley live in are helpful fore sure to solve that itchy-scratchy problem. One thing that has to be taken into account may be her coat. Is it thick and therefore suited for colder climates? Or is it short and thin?
Anyway, to me it seems that the damp and humid climate during summer in Charleston has got something to do with her problem. As she doesn't seem to have issues during the winter months when the air is rather dry, it must be the humidity that gets to her.
Another thing: Fleas: While there seem to be only a few, please be aware that flea bites can cause an allergic reaction on the skin that can lead to scratching that seems to be out of all proportions. If you want to consider this - and I think you should - then you will have to think about flea protection for Haley. This means you may have to try a product that is applied on the skin and should last a month or so. I'm not too happy recommending this, but you may have to choose between the lesser of two evils. I don't know what types of flea protection for dogs are available in the United States, so I can't help you there with a product I would consider safe enough. Two common products here are Advantix and exspot (against fleas and ticks; ticks are quite a problem here, and dogs can get Lyme desease from their bites). We use exspot, and from my experience, it seems pretty safe. But of course, if my dog is reacting positively, that doesn't mean that this applies to all dogs. You may have to try it out. If you do so, and Haley doesn't display any adverse effects, then I would recommend to use it for a couple of months to see what it does to her itching/scratching. Best to start early spring, before it gets warm and humid.
Did you check Haleys skin by trying to part her coat with your fingers? Is it ever reddish/inflamed? If so, it could be an indication that she is allergic to fleas and/or humid weather conditions.
Another thing to consider: dogs have plenty of bacteria on their skin, and they can irritate their skin as well, especially when it's warm and humid. A common condition here is the so-called hot spot, where a dog gets infected skin simply because the coat is drying to slow after a swim in the lake/river or whatever. The tiniest scratch can then be the "attack-point" for bacteria; and usually you would have to use antibiotics to keep that in check. Toby is such a sufferer. He loves water, but has a very dense coat. So, during the warmer month, he would use anything that looks wet enough for a bath or a swim. I had to learn to dry him afterwards with a hairdryer to make sure no hot spots can develop. As he is a huge dog, that hair-drying really takes some time. :-)
Important: Should Haley have skin problems because of scratching/fleas/whatever, ask RG if his RG's MEDICATED SKIN CREAM can be applied to dogs as well.
You are not weird by making sure that no appliances are active or even in stand-by while you are away and Haley's at home. In fact, that's the most responsible thing to do. Everybody should do that, actually. It helps to prevent accidental fires. And it has financial/environmental adavntages as well: any stand-by electrical product like TVs, DVD-players, Stereos etc. need energy when not truly shut off/unplugged. So all the people laughing at you do something you don't: they throw money out the window and make sure ever more energy is needed, with all its consequences.
Haleys is getting clearly a good diet rich in variety, so there's little chance the itching is based on her food.
Don't worry too much about the cats and parasites. Of course there's always a chance that Haley could pick up something from them, but I would say this is rather uncommon. As I see it, these cats are most annoying (we've got the problem with the cat pee all around our house as well), but not much more.
To make a long post finally short: in Haleys case, I would concentrate on two things right now: first the possibilty of allergies based on flea bites, and second the humidity during the warmer time of the year. If she is taking swims during that time, make sure you rub her off with a towel as thouroughly as possible. Should she have a thick coat, you may want to try the hairdryer trick as well.
I hope that what I layed out here will be of use to Haley, she sure deserves to be released from that annoying itch.