I don't know much about your physical conditioning, but some people, especially those over 55, can't handle constant day and day out long rides, older people need a bit more time off. The century training programs show one day off a week, but for older people there are recommendations that they take 2 days off, not in roll but rather in the middle of a week day training program and again at the end of the one long weekend ride. My wife and I are both 60, she lead a sedentary lifestyle and is paying for it, so she's trying to ride a bike now, I designed a training program but after about 4 weeks it became apparent she needed a second day off. Even though I'm also 60 I've been riding all my life so one day off is all I need. I think for your training you should take a mid week day off and again at the end of the longer weekend ride, but I don't know you so you have to be the judge of that from how tired you feel. That only applies for the training, once you do the tour 4 days won't be as bad because at the end of 4 days you're resting.

Again this all an opinion, you have to decide what's best for you.