I concurr with Sweeney on choosing a Tekonsha brake controller. I have been using a Tekonsha P2 unit for about 3 years with excellent results. I have towed on Interstates, In the Rocky mountains, city traffic in good weather and bad. The brake controller has performed flawlessly under all conditions. I'm only familiar with the P2 and P3 varients. I believe that either of them are capable of handling multiple axle braking systems.
I'm sure that Tekonsha's web site will offer a waelth of information as well as etrailer.com