Chicken Tractor tilling

When I finally finished the chicken tractor (with only limited help from Matt - he let me use the circular saw!) it became clear that this chicken tractor could best be described as a '1st draft.'  However, I'm being realistic and I know its unlikely that I will build (or ask Matt to build) a second one anytime soon.  This chicken tractor is kinda heavy, so, that would be the first thing I'd change.  I'd like to make it from bamboo - but wouldn't it have to be tied together?  Ok - maybe there will be a 2nd draft. 

But - it works fine.  I back it up to the coop like you would a wheelbarrow, I open the door on the chicken tractor, put a flap down on the door to the pen (to keep the hens from jumping over the tractor) and shoo them in.  If this sounds somewhat rigged - it definitely is.  Like I said - I was the brains behind this one.  

So far, the girls don't seem to mind it.  However, I believe that some people keep their hens in the tractors for several days or until the hens have effectively tilled the land beneath them.  In that time, where do the hens lay their eggs?  I'm tempted to not use the tractor that often because I don't want to disturb their laying cycle, I think I've already disturbed them enough.  I put them in a rolling cage! they were clearly confused by this.  Have you ever seen zookeepers move the penguins?  That's what I had in mind, but the girls didn't really 'get it'...maybe this takes practice.  I wanted the tractor to protect the hens while they are out grazing as much as I wanted it for them to aerate the garden.