Hi Jules,
I did have an Equalizer WDH installed and the 4Runner towing the 171 was stable, my biggest issue was the transmission and the inability of the TV to keep at a somewhat consistent speed in Drive. The 03 4Runner has a 4 speed auto transmission, and in Drive on I-39 in central Wisconsin it could not keep a consistent speed, and continued to shift back and forth as I tried to maintain 60-65 mph. As another poster mentioned I tried driving in 3rd gear, which on the interstate at 60-65 was over 3000 rpm's.
To each their own, but I was not looking forward to driving to California and back in 3rd gear on a month long trip. Just my experience only!
The 4Runner and subsequent Titan are both pre-wired for brake controller's, so I removed and re-installed the brake controller in the Titan in 15 minutes, just had to get the new adapter, it was fairly easy. The dealer I purchased the 171 from installed the brake controller, and allowed me to test pull the 171 before I committed to the purchase.