Wondering if anyone has taken their cats in a trailer? It would seem that they would certainly need to be in a carrier, tied down so that it doesn't slide around. What about temperature? My trailer...
Only concern I would have is the heat. In a crate secured in place, they may not be happy but they are in no great danger from the ride...but the heat...
If you ever saw an old WWII movie where the Japs would put people in a metal shed as punishment...yeah it's like that. Very easy even in relatively cool weather for the interior to get north of a 110-120F.