Hey there. Well, I did suggest soloing on your other thread, so I guess it's no surprise I think you can do it alone. You come across as someone who has her head on straight, which I think is the most important factor.
The biggest hazard of bike touring is traffic. This is the same if you are alone or in a pair, and gender doesn't matter. I guess there's a chance that you could be injured and alone with no one to help you, but most places have at least a few cars an hour, and this also doesn't really relate to gender much - many of us, male and female, take this risk.
The hazard you are worried about - people, specifically, creepy men. Well there are a few. But, not that many, esepcially in more rural areas. I can't speak for the southeast USA, since I avoid it, and I would sort of guess there is a bit more people-danger there than in other rural areas, but in the west and plains, I had almost 100% good people experiences, and the few bad ones, you just have to keep your radar on, and be smart. If someone seems creepy, assume he is and take measures to not get in trouble - like don't say where you are camping, or take hotel room if you can't find a safe feeling place to camp. Meet camp hosts and tell them you are solo, they will look out for you. That kind of thing.
Also, I find projecting an air of confidence and being totally non-sexy / non-flirty seems to help. At least, it helps me psychologically, from not feeling vulnerable.
The other thing you can do to feel safer solo is learn a little more about your bike so you can feel confident to do road side repairs.
As to pace, I am an *avid* cyclist, but am a small person. I average 55 or 60 miles/day for riding days when touring, not including the day off I take every 7-10 days. I find that the weight of my loaded bike affects my speed much more than it does for bigger people. Last summer I had an opportunity to ride loaded with a couple of guys who I normally do day rides with. I was consistently much faster than them on my road bike and consistently much slower than them on my loaded tour bike. I attribute this to the raw power it takes to move the extra mass - I have power to weight, but not much raw power.
So, if you are a smaller person, take that into account - when you hear guys (staeph1, I can here you coming) say they average xx miles / day and don't take rest days, you really need to discover for yourself what your daily milage will be. Most people say 60/day, some people definitely do a lot more, others a lot less. If you have to ballpark your pace, I would use 60 not 75 unless you are a very strong rider, even racer level.
One thing you can do to mitigate the uncertainty of your pace is don't book a ticket home until you're getting within a couple of weeks of where you are finishing, so you don't have a deadline. Also, flexibility of other parts of your plan - route, final destination, etc. - can really relieve a lot of stress along the way. If you have weather you need to wait out, get sick, fall in love and want to hang out for a week, you can.
Have fun!
oh yeah, Lewis & Clark is great