In Canada I just (Jan 2018) got a $5000 rebate off a left over 2018 plus the dealer discount. It was very late in the year for a 2018 though. It worked out well for me though as I was getting rid of my 2018 F150 because of all the issues with it so helped ease that pain a bit.Rebates were $4,500 back in 2008 on the first generation Ridgeline. Seems like there was a $3,000 rebate on my 2010 and they may have been at high at $5,000-$5,500 at one time.
The second generation Ridgeline currently has a $750 loyalty rebate for current Honda owners until at least 2/28.
Historically, Honda has offered very few incentives other than lower-interest finance offers on "last year's models".