As an experiment I wired a near dead group 24 battery to the buss bar, less than 2 feet of cable. It never went into bulk mode, and it didn't give out much more than the 11 amps it gave out with the stock install which is about 20 feet of #6. Maybe my unit was defective, but I am not the only one that no matter how hard we tried it never went into like a bulk mode. If you are getting 65 amps, out of a 55 amp unit, then you are doing very well and treasure that unit but most people don't want to go to the effort like you did with making a box and moving the unit around to compensate for a bad design and they may not duplicate your results.
Glancing through your link you must have a large battery bank, 400 plus ah, how large and what type of batteries?