Springfield
I recall picking up a cut down springfield 1911, recently. I'm sorry, as I don't recall the model name/number, but it was a shock to my hand, as the trigger and backstrap were much closer together than any other 1911 style gun I'd ever picked up. Turned out that it was built around the .45 GAP, rather than .45 ACP. the round is shorter, therefore the front to back size on the grip was smaller. also, 1911 style, so it's SA.
Also, there are a lot of SA revolvers out there nowadays with itty bitty grip frames on them. Ruger's Single Six, in .32 H&R Mag, and a host of smaller model Ubertis. Don't discount the .32 H&R, it's a pretty potent little round, unlike the .32 ACP, and others. Only downside to the SA revolver is that they are slower to reload. not necessarily slower to shoot, though. With proper technique, numerous cowboy shooters can get off ten rounds, out of two pistols, in the four second range.
Hope that helped.
~~~Mat
PS: I don't have a ruler handy, but a side by side comparison has revealed three things.
1: Your wife has very small hands (I realize that this is obvious to you, but, being a visual person, just became obvious to me). My trigger finger, when fully extended, is long enough to reach the muzzle of my P32. This places the trigger at about second knuckle, (from the fingertip.)
2: For a Single Action Revolver comparison, I picked up one of my match guns, and found the reach to the trigger to be nearly 3/4" shorter, using my normal grip. That should buy her enough room to get on the trigger. Also, bear in mind, this is a full sized Peacemaker clone, with fairly fat grips. It is available in calibers ranging from .22 LR all the way up to .45 Colt. Ruger's New Vaquero has similar size grip frame, with slimmer grips than mine have. It would also allow the gun to be carried fully loaded. If that's not small enough, you can still look at the small framed SA's.
3: You might try going to a SASS match. Take her along, and you'll have cowboys tripping over themselves finding guns for her to try, and showing her how to shoot them.
4: I'll never, ever complain about having small hands again.