I have two dogs and live in Northern California and we are yet to have issues of the dogs getting too hot. Step one is we prop the lower corners of our side pannels (have the embassy hinge and are yet to hear, see any issues). Step two is we use these. We only really need step two when the ambient outside temperature is over 95.
Just like any topper when stopped we don’t leave them alone when we stop. If we do we make sure to park in the shade and that the ambient temp is 75 or under.
Here is a link to a previous post of mine in a thread that covers similar issues.
(As a side note my partner is a Veterinarian and she keeps a close eye on them and we have driven through 100+ degree heat four times now without an issues. We just make sure to stop every two hours and water them and check on their vests. A healthy dog is a happy dog.)