I respectfully recommend against the distances you think you will do. 30 km daily is a more reasonable distance, at least IMHO. But, you will develop a pace once you start out.
Some years back, I recall reading one account in a book, of a fellow from Canada who walked from Saint Jean Pied de Port, fueled by Mars bars and Coke, in only 20 days. But, why?
Doing so many km daily, you are focusing more on the destination than the journey. Most of us have come to realize that the journey IS the destination. Paying attention to everything around you, learning, absorbing, reflecting, meditating, appreciating, interacting, learning more, etc.
It truly is a remarkable life-affecting experience. Like a fine wine or painting, one should savor it, drinking and drawing in the entirety of the experience. This necessarily takes more time than a passing glance as you rush by to attain your daily distance goal.
But, this said, I wish you well on your journey.
Personal safety is not an issue, per se. Walking alone is, or can lead to unpleasant situations. Walking with or near others solves this concern. My advice for single walkers, both genders, is to seek out walking partner(s) from where you stayed last night and ask them if you can 'tag along' with them for the day.
This does NOT mean they are your new best friends. They are just fellow pilgrims headed in the same direction, whose names you may know, and who you will keep in either eyesight or hearing distance as you walk. They become your daily 'safety net' or backup.
Should you feel worried during the day, you can either speed up or slow down to walk with these folks, or blow your whistle...you ARE carrying a whistle for signalling? Even I carry one... If you were to fall off a trail injured it is a standard method for summoning help. Three long blasts, followed by three short, and repeat.
However, if you walk the 'jet-propelled' pace you envision, it is not likely you are going to find a fellow 'rabbit' to accompany you. Just sayin... I understand that you have limited days to do this, but there are other alternatives to cover the distance.
Another way to cover the distance is to leap-frog over sections that appear less appealing to you. All along the
Camino Frances, there are bus services connecting most all the standard towns. So, if you wanted to walk from Pamplona to Logrono, then bus to Burgos, it is easily done.
I sometimes use this method to skip a day or half-day walking into or out of a large city. The large industrial belts of warehouses, highways and big box stores surrounding some of them suck the enjoyment out of my day, at least IMHO. So, I will sometimes take a morning bus from the previous night's town and just avoid these sections. Over the entire route, you can recover several days doing this.
Just FYI, in the
Brierley guide book, these industrial areas are shaded light grey.
The sole restriction to keep in mind is that, to qualify for the Compostela once you reach the Pilgrim Office at Santiago, you MUST walk the FINAL 100 km on any route into Santiago. Over this 100 km or so segment (118 from Sarria actually) you must get TWO SELLOS / stamps daily. Before that, one per day is acceptable.
Also, if you do persevere and DO walk from Sarria to Santiago in only 2 - 3 days instead of the normal five days, expect to be grilled by Pilgrim Office staff. Folks who cheat commonly show up with stamps covering really, really fast transit times from Sarria. Even those with many stamps per day are questioned to determine their veracity. They are always taken aside and questioned about specific architectural detail, places that one cannot miss in each town along the way, statues, cafes, churches, tourist places, etc.
My advice, even if you DO speedily walk your Camino, SLOW DOWN when you get to Sarria. Allow a minimum of four days. For most of us, once we hit Sarria, we do not WANT to arrive at Santiago. Yet, that town is the signal that the end is coming.
I hope this helps. Let us know how you get on...