Ok wait, how did you use the wheelbarrow? How did leaning against the wheelbarrow create that effect? Was the wheelbarrow tipped?
The actor just laid on top of it. fairly simple...no trick to it...you just lay on top of a wheelbarow.
Now with this method, pretty much whatever you do is gonna come out cheezy-looking. But it can be done cheezily well, think Sam Raimi.
If you fixed some sort of stilt to the front end of the wheelbarow, the actor could be elevated off the wheelbarow a bit, which would make it easier to cheat the shot. Also, I'd advise shooting in a widescreen format or cropping to a widescreen format, to make it easier to frame out the wheelbarow. And of course take the shot from a lower angle.
Depending on how fast you accelerate the wheelbarrow, you may want to lock off the steering mechanism, and make provision for the actor to ditch & roll easily if he has to...uh, safety first