For tips how to build a balanced tuner look at the website of PA0FRI.http://www.pa0fri.com/
He has lots of info and examples.
He also build and tested a lot of different tuners and tested them in range performance and efectivity.
He also has lots of ideas about how to build a simple antenna system.
I have build a tuner that is not very well balanced but I offered a bit of balance for versatility and very large tuning range.
It will tune open lines as well as it will do coaxial fed antennas.
It will do legal limit and some more to.
I do not have problems with RF in the shack though I can run high power.
Tuner is also only inches away from my rig.
An you can do funny things with ladder line hihi.
Look at this movie my don made of the ladder line in my shack.
As you can see my homebrew ladderline is also a bit larger and thicker. http://www.youtube.com/watch?v=3Ah3DYXCwcc
However my tuner is not a project you should undertake as a start.
It became rather bulky big and although I build it realy cheap, it would be very expensive to copy.
But it does a fine job in tuning my very small and humble balanced antennas.
Good luck with your project.