You would need to account for weather in that calculation, it’s not a simple matter of distance divided by speed = time, since the aircraft may be doing an air speed of 60 knots but be flying into a 20 knot wind, meaning it’s speed over the ground is only 40 knots. Most speed measurement on telemetry is airspeed.
I would be surprised if a full size guinea pig could exceed 40-50 mph over the ground, it’s big and floaty.
If you are going somewhere beyond visual range you should check your local laws and if they prohibit flying beyond Line of Sight (LOS) or above a fixed altitude you should NOT break those rules, they are there to protect you, people on the ground and general aviation pilots.
If you are going to fly somewhere in your guinea then I am sure everyone would love to know how!