Finally someone else that has used a trailer with surge brakes that knows they will stay applied all the way down the mountain. How much and how hot can't be determined until you do it...to many variables. From my experience they do not work well in mountains...over heat. On fairly flat ground where after being applied you accelerate and they release they work well.
OP, since it's easy to not have your brake lights come on when using your exhaust brake (my preferred option) I would go electric BUT getting the brake controller wired can be challenging. I ended up mounting mine in the engine compartment as everything you need is right there. Once you get the gain set (amount of braking) you do not need to change.
