+100 the fan.
Also, connecting the cadence and HR data is a nice to have, not actually required. If your trainer delivers power data over BlueTooth and your tablet has BlueTooth and can run TrainerRoad, you should have the bare minimum. If you add the fan.
Another option, again assuming power from the trainer over BlueTooth and ANT+ and you have BlueTooth on the tablet is:
- Load your workout.
- Disable WiFi on the tablet.
- Start your ride.
- Record data with the Garmin (trainer connected by ANT+).
- Use TR on the tablet to guide your workout (trainer on BlueTooth).
- Upload data from the Garmin and from Garmin Connect to TrainerRoad.
- After the Garmin data shows up in TR, enable WiFi on the tablet.
- You may end up with a separate entry for the TR-recorded data. If so, edit the ride and remove it from TSS and PRs.