I got that exact setup with the 2≠ 1500 lipos and love it, will try for that 37,000ft soon I'm only to 27,000 ft due to nerves.... any tips?
You likely will need batteries with more capacity to get 37000 feet, unless you have a location with low interference and on a hill where you can fly craft at low altitude. You need a day with no more than 4 mph wind and fly into the wind. I use P-mode with obstacle avoidance off. Use RTH to go home and hold pitch stick full forward for 33.6mph speed. Gives you a perfectly straight return home and a bit more speed than just P-mode (33.6 vs 32mph). If you have pushed the battery to the max, the auto landing will initiate at 11% battery. You have to push the elevator stick up a bit to maintain altitude in RTH mode. I've found that a battery weight of around 240 grams or less is plus dual XT60 battery mod (don't get the one with Y plug) about ideal, where Mavic flys very stable and at the normal speed as stock. If you go too heavy, like over 350 grams, the motors are pushed close to max thrust and consume sport mode levels of energy.