as another 23SS owner that has to deal with mountains, here's my input.
you need a brake controller since it required by law because the 23SS has electric brakes. any Prodigy BC is the best for the price.
you need a WDH with sway control, not just sway control. i have an '07 Avalanche and there's no way i'd tow it without one.
i love my Equal-i-zer because it's simple, has integrated sway control and is built in America.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC