Just to recap: I have extended one of my bicycles and turned it into a load-carrying "longbike", and have added a flatbed to it, as it were. But what to do when transporting something really long is called for?
Those wacky folks at xtracycle make something called a "LongLoader", which is an excellent thing but it was not available at the precise moment I felt the need to transport a roll of plastic netting that friends in the towns wanted for making trellises in their garden.
The problem with long stuff on a longbike is that the cargo will interfere with the pedaling, thus the "LongLoader": to make sure the long stuff, whatever it is, is placed at an angle.
A really easy way to achieve more or less the same is to jam a backpack down at the appropriate place. In the picture below it's easy to see how much room my there is for my feet.
I didn't say it was extremely clever.
The very observant will notice this is still a single speed contraption. I ended up spending so much time fiddling with the gears I decided doing without them would save me time. There's a lot to be said against single speed load bikes though, I really must say.