With total respect for your question, look at your own rig, and think about where you put the things you put inside the rig. I know, in my case, almost all my storage goes ahead of the axles. My one ton can handle a lot, and it's lightly loaded compared to when it carried a camper. Having said that, it's heavily loaded by the weight behind it, and I really notice that when I have that weight behind me going downhill.
Putting on the brakes and trying to slow down coming into a downhill tight curve is very nerve-wracking and not a lot of fun, but asking the transmission to slow the whole rig down is equally nerve-wracking too. If you are close to maximum, and looking for advice, don't let fear and common sense hold you back. Get a better truck, or a lighter rig.