If you can ride a century you can probably string 4 of them together.

I signed up for a Quint x 100 a couple of years ago. 100 miles a day for 5 days.
We made it through 4 days and probably would have made the last day except my son-in-law was in a bad accident and broke his front fork. That kind of put a end to our trip.

I know that I'm a stronger rider today than I was back then so if you're not fighting hills or awful headwinds or driving rain (we had all three) you'll be fine.