I keep my hair short all the time, and buzz it all off before a long hunting trip. A greasy head of matted hair is the worst feeling for me.
I bring a full-sized toothbrush and a travel-sized paste. I bring dawn dish soap to shower, really cuts through the grime. Travel sized deodorant, contact cleanser-solution, extra contacts, and eyeglasses.
I have used the solar showers on backpack hunts, if you've got a spot that gets plenty of sun they work great. We set up camp in a river canyon in CA once though, daytime temps hit the 60's each day, but since we were down in the canyon the camp only got hit by the sun in the middle of the day. By nightfall, when I was done hunting, the water in the shower bags would be cold again. Still felt good to get clean though.
For truck based camps, I bought a 2.5 gallon spray bottle like you'd use to spray weeds. I heat up a couple gallons of water on the camp stove and use that for a hot shower. It actually works really well, the wand sprays so fine of a mist that 2 guys can shower with it and usually have water left over.
I use the Balleck Dry Shower, but don't plan to buy more once I've gone through it. It does exactly what they advertise but I just don't care for the dusty feeling it leaves. That's a YMMV item.
I use a decent baking soda toothpaste, and I keep my hair combed because if I don't, my scalp gets sore after wearing a fleece hat for a week straight.
To keep the smell down I do a pits-and-privates wash morning and night with a biodegradable wet-wipe. I forgot the brand, but they're all pretty similar. I chose one that's odor-free. Supposedly you can bury these but I never feel right doing that so I pack them out. They're really light and I always have other trash coming out anyway. <shrug>
I also clean my feet daily or I get athlete's foot. On that note I also use a mini travel bottle of Gold Bond foot powder every time I change my socks. I change my socks twice a day (morning and mid-day).
For deodorant I use the Scent Killer Gold. This works really well for me. There's a similar bath soap product I use if I happen to be somewhere with a shower.
I know it's all working if I get home from a trip and my wife will hug me before making me shower!
I missed a comment above about gum. I second that one. I like the Mentos one because I don't take the whole container, just 2x/day in the same baggie where I carry my meds. I feel like the hard shell gums stay clean in there. Anyway human breath is one of the most potent odor sources we have - definitely keep your mouth fresh!
For what it's worth I tried the "Dead Down Wind" mouth spray. I don't personally recommend it. It may or may not work but felt like it wore off really quickly, and the bottle leaked. It's an oily spray, and it was a mess to clean up. It's also an inexplicably heavy item to take backpacking. Not worth it IMO.
For meds I have individually labeled baggies in one larger ziploc (lighter than any hard-side pill bottles). I carry:
- 4x benadryl anti-histamine tablets
- 2x emetrol anti-nausea
- 1x 1000mg sugar tab (sometimes I hike with a diabetic, they self-manage but...)
- 12x aspirin
- 12x caffeine tablets (low dose, not the Jet-Alert ones)
- 4x Gas-X
If you carry anything at all, I'd suggest considering the benadryl. They're tiny, weigh almost nothing, and can help deal with all kinds of reactions from skin to respiratory. And if you ever find yourself with somebody who has a nut or bee sting allergy (and maybe didn't even know it, so they don't have an Epi-Pen) it's not a fix, but could buy you enough time to get them to the ER. Most survival/emergency kits have the basic analgesics like Tylenol but never seem to include this.