Mountain Biking With Apple Watch

Does anyone have a solution for tracking a mountain bike (off road) ride on Apple Watch and getting an accurate calorie count? I’ve read up in old threads and there wasn’t a real solution. It’s clearly calibrated for road cycling as it puts a priority on speed over heart rate. Mountain biking is slower but I have a higher heart rate. I’ve used indoor cycling and gotten a much higher calorie count but would like to use the gps feature.