It might just be the 25% grade and the weight . 25% seems like a lot.
Have you ever traveled this hill before without this problem ? or was this a one time/first time occurrence ?
Did all 4 brakes smoke or just the front. check proportioning valve, it was a problem on some dodge trucks . The front brakes were doing most all the work and overheating. Especially if you are using a lift kit.
I had a problem with brakes overheating and the brake fluid was changed to a higher temp. fluid. No more problems after that.
Im not really sure if the higher temp fluid made the differnce or if there was moisture in the system. But , it was flushed and replaced with the new stuff.
http://www.stoptech.com/technical-support/technical-white-papers/brake-fluid