Yes, ridewithgps or strava to record your ride. Perhaps a handlebar phone holder if you want to see it while you ride, but it works fine in a pocket.
I've seen the rule of thumb here that a rider can (barely) finish a day ride that matches their weekly mileage. It won't be fun!
Most riders can go farther on the event than their longest recent ride. It's the motivation to finish and the other riders company along the way. With a 62 mile Metric goal, I'd want to ride 40 miles fairly comfortably, and do at least one 50-55 mile training ride a couple of weeks before the event -- to prove I can handle the distance, and to sort out any saddle, shoe, or hand problems.
If the event has hills, climbing practice is key. Hills aren't bad if you figure out your pacing and gearing.