First: have you tried using a post driver like this one? I've got really rocky ground too, and I know what you mean about getting a hammer on it. The post driver may help you get your force directed into the stake properly.
If you want less manual labor, you could see if you can rent a powered post driver like this. I've never used one, but I'd guess you'll want to make sure you've got really heavy duty stakes.
Second: when I try to drive a stake, I usually have to make 2-4 attempts on each stake. Drive it, realize I've hit a really big rock, move 6", try again. Sometimes I use a digging bar as a probe to find a path where I can get a stake in. It's still brute force, though.
Third: sorry, but I think five foot stakes aren't going to help you in your battle with deer. Unless there are lots of other distractions in your neighborhood, they will easily jump a five foot fence to get whatever you're growing. Last year I had two strands of electric fence with the top strand at 7' high, and 5' welded wire on the bottom. They still got in... I had to add a second perimeter of electric fence 5' high about 6' outside the inner fence before they stopped getting in.