Here is what I did to convert from a two tank setup to a single tank setup. I just travelled 3000 kilometers and have had no problems. Sorry, but I don't have a camera, to show you a picture, but I can describe.
1) Buy a special cap to cap off the unused hose end. Some RV shops have them.
2) You know where the two tank crossbar hooks onto the propane
tank? Well, replace the one of the propane
tanks with a piece square steel tubing of the same height that the tank takes up (the height of the slot). Simply use the existing propane
clamp to clamp onto the piece of steel instead of the tank you don't want. (in my case, I used a piece of unistrut). Works like a charm.
I really hated having to carry the extra tank, but didn't want to permanently rework the arrangement. This way, I can go back to two tanks any time.
I'll need to find a digital camera to show you some time..........