We will be relocating from Boston to Phoenix later this fall and I'm wondering if I would need an exhaust brake. I will be towing a 16ft 7000lb cargo trailer with electric brakes loaded to the max likely traveling on I80, I70, I44, I40 and I17. There are likely some hills on these highways but I don't think my load will be heavy enough to justify spending at least $1k for the brake kit. What do you guys think?