Leaderboard

Yakima and Thule do sell tracks that have a universal u-channel design as well as a few other companies. It's a different style than the OEM in that they are flat and flush with the channel of the van. I like that feature so it's flush when racks are not in use. Depends on how you plan to use your racks and how often. See pics in the thread linked below.

A lot of options via OBDII . Plenty of free and paid apps. Or you can use a Scan Gauge or scan tool. I am using Torque Pro. FORScan is better, but only for Ford. Torque Pro will work on other cars.

Easiest with a scanner app like Forscan. There's a parameter in the Body Control Module called Transmission Fluid Temperature (BCM_TFT) that has the name and behavior that one would expect, Forscan makes it easy to pipe to a gauge icon on your phone screen. (There are also a few dozen other transmission-related parameters in the BCM to puzzle over... the ones for actual gear selected and torque converter slip have been pretty interesting to watch.)