Background: The reason Carloop is feeling hot is because the linear regulator is pushing a lot of current when the cellular modem is active, thus heating up the entire board.
Solution: Replace the Linear Regulator with a Switched Mode Power Supply from Pololu.
What you'll need
Step 1: Unsolder the stock linear voltage regulator and clean up the remaining solder with the desoldering braid.
Step 2: Solder the 3 angled pins to VIN, GND and VOUT on the Pololu 5V Switched Mode Power Supply
Step 3: Trim the pins and remove the black plastic insulator
Step 4: Solder in place of the linear voltage regulator as shown: