2x4 with line set insulation for padding You will have to put the second in like saw horses so you can remove it. Or the like My 2¢
Ive been thinking about this for awhile. Since they are e-bikes they should be transported so the batteries dont get damaged, explode and set the county on fire. It’s a very real possibility in a dry summer. This is how I would proceed. 1) Line the bikes up next to each. One bike backward one bike forward. So for 12 bikes a total of 6 would be facing forward and 6 backwards but alternating. 2) Take a long heavy vinyl coated cable with a loop at each end and feed it through the frames. You may have to measure this to get the right length cable. 3) Bring both loops to the back of your tow vehicle and lock them to the bumper hitch loops. 4) Drive at elevated speeds down the highway and drive off the nearest bridge in California. Be sure to jump out of the vehicle before the vehicle and the shit e-bikes go flying into the river below. Just say’n That’s what I’d do.
I appreciate the thoughtful response! I'm trying to set something up starting next summer that will see me transporting bikes at least twice a week, so yes, hoping to get the process as efficient and safe as possible. Setting up something so 1 person can do it is key.