Reminds me of that song :Trailer for sale or rent by Roger Miller King of the Road.
I've been thinking of either buying a trailer or making one and I got to looking on the web as usual. For anyone also thinking about it or to get ideas have a look here. Lots of great tips, designs etc http://www.singlewheel.com/
I'm 70 today but I was 9 when I saw a single wheel trailer all over the road with it's load too... using a single wheel the beast is very unstable, if it loses air the trailer gose down and so does the biker... If it has a blow out both the trailer goes down and so does the biker... To attach the one wheel trailer to the bike you need a bar thats as wide as the bike to attach it too... VERY BAD DESINE FOR A 2 WHEELED MOTORCYCLE
I have a 5x8 Enclosed Cargo Trailer that I picked up for a reasonable price.
Installed hardware on the floor and walls myself (parts are pretty cheap, bolts at the hardware store) - all you need is a drill, some wrenches and maybe a partner to hold the "outside" while you tighten the "inside".
Depending on the vintage you might need a 5x10. As noted, I have a 5x8 - I can get two m/c's in the trailer, one nose forward, one nose to the rear. When I haul one m/c it sits right on the center line.
You can pick up a lot of those trailers for under $1500, frequently under $1000. No more than $100 worth of hardware and your m/c rides dry, out of sight, and secure.