Here are the facts:
The Ridgeline is very similar to the Pilot with beefed up rear suspension. Using a WDH is very common, and is acceptable. See below for Honda's exact concern from the owners manual.
I towed a 23...technically 25 foot TT with our Pilot and the biggest upgrade was tires. I put stiff low profile UHP tires on, and it was stable as could be. But you always knew the TT was back there. It was spec at 3600 dry, weighed 3800 off the dealer lot, and 4100 loaded.
The V6 and trans work very well together with OD off most of the time. There is ample power even on 8% grades.
What you really need to ask yourself is how often and how far you will tow with the Ridgeline. If you are doing in state and tri-state trips...no problem. But any further and it will wear on you because you can feel the trailer more than you would bigger TV's. We ended up buying a large SUV for towing nationally the next few years, something we never planned on. The upgrade was done for full day driving comfort, and high elevation power.