I'm not sure why brakes are a concern. I can show NHTSA data that shows that disc brakes are no safer than drum. The BIGGEST safety measure would be switching to dual systems rather than disc.
My M35a2 at 12,000lbs with an M105 trailer (another ton) stopped perfectly fine with drum brakes.
Same for my 13,000lbs CCKW.. stopping on Pennsylvania hills is no problem for a drum brakes on a truck that big.
