Not sure which gasser folks are using but with the Ford V10s most will have a Haul/Tow option. Heading down a steep grade - Monteagle is a little tense the first time - simply follow the instruction given by the former instructor about stabs. The tranny in Haul/Tow will brake considerably. I've driven thousands of miles with heavy equipment on flatbeds and now several thousand with a gasser RV. No problems - just pay attention and let your vehicle help.
Maybe I have different rear gears but I was able to maintain and easy 45 mph without worrying about the engine over revving.
Oh yeah - took my DW a bit to gain the confidence to ride down these but now is sure we are good to go.
US Army Retired - loving it in our Challenger 37TB.