This is one those happy accidents that happen in life. I actually had put this together to carry merchandise around for my work, and it occurred to me that it could very easily be use for bugging out. And oh so simple of an idea it was to start with!
It goes like this: Take a utility trailer (whatever size you have) strap down two x-cargo rooftop cargo carriers and voila! you have a quick, simple rainproof bug out cargo trailer!
These carriers are actually easy to find. I bought one at my local Salvation Army thrift store (one of my favorite places to shop!) and the other I got FREE as a curb alert. I used ratchet tie down straps from Walmart to hold them down. You will find there are four metal slots around the base of each carrier just right for the straps. As extra security, I put bungees over the tops of the carriers. I spent about $50 total for this project.
My trailer happens to be 5' x 8' in size, but this could be done on a utility trailer of virtually any size. Longer trailers could take three carriers or more. Just more cargo space for your supplies and food as you escape the hordes of zombies craving your braiiiiins!