I don’t find that Stuebbens tend to fit Morgans well. They also tend to have longer tree points, if I remember correctly.
My Morgans are basically on the border of needing a hoop tree, but I typically find the fit is just not quite right. That said, it might still be worth trying a hoop tree on your horse, even if “on paper” it seems like it’s not the best option. As soloudinhere points out, sometimes what makes our horses happiest is not what, in theory, should “be best.”
Ultimately, my horses decided they liked an XW County Conquest the best. FancyThat’s lovely Morgan mare likes her County Innovation (I think it’s an XW). County saddles have shorter tree points. The Innovation is a bit wider than the like-sized Conquest or Stabilizer, but is also a bit more curvy front-to-back. Honestly, it’s worth having your County rep out.
Prestige could possibly be another option; it was suggested my mare, who is a bit narrower than my gelding, would be a 36cm, which is the widest they come before having to special-order a 37cm. (VTO saddlery told me they could not open a non-37cm tree up enough to make it a 37cm.) I never did try a Prestige, but they are more curvy front-to-back than many of the saddles you’ve tried.