Congrats on the nice ride! My longest ride is 36.5 so far, a supported ride like the one you are considering. I completed it ok although there were quite a few hills and a tremendous headwind the last 12 miles, along high heat and high humidity close to the end.

There was some discomfort near the end, especially with my flat handle bars and getting enough hand positions. You might want to add some end bars before the ride. I was on a hybrid for that ride.

There were only two rest stops that ride, and I really amazed myself with how far I could ride without a break! I did stop one other time at the top of a big hill to catch my breath and, of course, could have stopped any time I wanted.

The ride gave me a lot of self-confidence and was very positive! I'm 51 so I made sure I was well rested the day before the ride and had a "recovery" day the day after, took some gel, in addition to the goodies at the rest stops, and drank a good sport drink all during the ride.

You oughta go for it!