Yes, Yes and Yes!!!
I make HP salt bars and use them as shampoo and body bars. They are super easy. In fact, I think they are easier than CP salt bars.
Here's my recipe. As you can see, it's really hard.
100% coconut oil
20% superfat
That's right - 20% superfat. While it is a lot of coconut, the high superfat counteracts any drying effects.
Anyway, run this recipe through Soap Calc to get your amounts of oil/water/lye for whatever size batch you want. I usually make a 2 pound batch because the salt you put in adds at least a pound or more to the finished amount of soap.
Mix and cook your soap like normal. It should cook at low for about 45 minutes. Once you reach vaseline stage and the soap no longer zaps, turn off the crockpot and add your fragrance/color and then salt. Now, the amount of salt is up to you, but I like at least 50%, if not 75%. I think a cup of salt per pound of oil works really well. Just add until you think the soap can't hold anymore. I use Morton's non-iodized table salt.
Get your soap into your molds quick, because my first batch (1lb) set up within 5 minutes. I'm not kidding you. As soon as the bars are cool, they are hard as rocks. If you use individual molds, then you should be fine just leaving them to cool, but if you get a single mold, then get your soap in the mold, let it cool slightly and then cut as soon as the soap stays together or you will have one very large salt bar.
My salt bars were ready to use right after I made them, but the lather gets better the longer they sit. They don't really lather like crazy in my hair, but they clean and rinse out really well. Oh, and don't use Epsom or Dead Sea salt because they don't work. At all. Regular table salt makes great HP salt bars.