Way to go, Marlene! You experiences down there sounded familiar to
me
The Grand Canyon XP, in my mind, is the ideal "first" multi-day for a horse
to do.
With my horse, I did a few 50's and then targeted the Grand Canyon XP as
the ideal (then) 3-day multi-day for him....I liked the Duck's format, I liked
the time of year (October, after a focused Spring and Summer of riding) and I
loved that experience.
The following year, I targeted Bryce Canyon as my horse's (BTR Ranger)
"first" five-day multi-day....which he did. Again, the Duck's format
(which, as you know, and this is MY interpretation of it, is simply, "you are
responsible for your horse, if you like him, you'll ride as if you do") and the
trails were what I wanted for Ranger and felt he needed.
He learned a lot from those rides, as did I.
You'll find 100 miles of endurance quite doable, now. And, GOOD LUCK
with that, too.