I read "100K" as 100 kilometers, so 66 miles. That's about 6-7 hrs in the saddle if you use 10 mph/16kmh as the avg. spd. Are you in shape for this, noting that you are not really giving us any useful information as to overall distance and terrain. If it's flat Holland/Delaware, that's one thing. Dolomites/Vermont is something else. Age is a factor as well as this might be doable for a 25 yr old, but a challenge for somebody 65. The cross country tour YT I watched last year of a couple in their early 60's, had them as very fit and experienced cyclists managing 35-45 miles per day with loaded bikes. Yet I had a co-worker in his late 20's, also a Cat 3 racer, did non=supported cross country in 6 weeks and averaging 60-70 per day.

More info as to total distance and location would be useful to give better advice.