Thanks for the encouragement Rick and Penny.
From the shore excursion blurb on the HAL website it says the tour goes to Posadas Barrancas, it is not overnight; it leaves at 5:30 am and returns 18 hours later with a boxed meal breakfast and afternoon snack. A luncheon is served at the train endpoint mountain town and there to be is a folk dancing presentation also. It's a long day and an expensive excursion but it is the only way we thought we'd get to see Copper Canyon. So "In for a penny, in for a pound."
I hope somebody who's done it can help us prepare, but even if not we'll go with a spirit of adventure...and let you know how it was!
PS Rick, We haven't been on Ryndam, but last year we sailed her sister ship, Maasdam, 11 days eastern Caribbean. The ship was elegant and very comfortable and friendly. If the folks you know found Copper Canyon something to rave about as being on par with raving about the ship, I'll assume we've made an excellent choice.
Any guidance on parking in San Diego?...oh I guess I should ask on the ports page. oops.