Rather than the bikes traveling outside in the weather ours ride inside, either in the truck or trailer. The trick is that they are folding bikes, www.downtube.com If traveling in the trailer there is no need to fold them. They lay against the sofa with one of the runner mats between them & sofa.
In the truck they are folded but it takes about 6 blocks of foam squished between them to stop the rattling. With the bikes inside there is still room for the Honda 2000 & some other stuff. Nice having a crewcab sometimes.