Ranger94...thank you for your service...
As to the Judge etc question...here's my experience, albeit with only one Judge..
A friend brought one out to our farm for a try out; bought it for exactly the same reasons you have stated...for his wife's less than proficient use.
The Judge in question had a trigger pull that we subsequently found that she needed two hands to pull...two fingers on the trigger, and as a result she couldn't keep it on an 8x11 piece of printer paper at 10 yds.
As to the accuracy and penetration...the Federal buckshot loads we tried that day would not penetrate one of my 1x6 fifteen year old poplar fence rails...whether they'd have done terminal damage to an intruder, I can't say. The spread at five yards, the same distance that's found in most bedrooms or living rooms in most houses short of a McMansion, was 5 inches. To me that says that the thought that a "shotgun spread" of buckshot will make up for lack of accuracy with normal pistol rounds is illusory, at across the bedroom ranges.
The .45 LC rounds keyholed at 10 yards....but did penetrate...and the group was about the same as the buck shot...5" across with me doing the firing.
In summation, I wouldn't trust my life or that of my family members to any of the current iteration of .410/.45LC revolvers...it's a concept with great advertising hype, but not a viable answer to home defense questions.
As you've said, practice to make her proficient is not going to happen...but the alternative may be worse. If she needs the use of a handgun, then you need to force the issue of practice. With three children, defending herself and them in the event that you are not there, is an enormous task. As to where to store the piece that you decide on, the lock box may be the answer, but maybe it should be in her normal haunts...like the kitchen. If you had a break-in, I just can't see her abandoning the kids while she runs upstairs to the lock box under the bed...maybe up on top of the fridge or next to the phone....
I'm retired, wife is 62, and we've had guns for defense since our boys were the ages of your children....and long before lock boxes were available. We kept a revolver in the front cloak closet next to the front door, hanging from a nail driven into the soffit above and inside of the door..within easy reach for her but out of sight. It was a Smith, and at the time my sons couldn't pull the trigger, but I had no illusions that they eventually knew where we had it. I made her practice until she could handle it and keep 'em on a sheet of typing paper at 15 feet...in actuality, she did far better than that over time.
It worried me then, keeping a gun accessible in house with small curious children in it, and it still does now, thinking back on it...but our address at the time made it an absolute necessity for a number of years. I guess what I'm saying to you is that a lot of thought needs to go into that part of the equation. In my opinion, if a gun is necessary then the lock box is the answer, but put it downstairs..and teach her to use a revolver with light loads...the .38 wadcutter in target velocities is a pretty good defensive round...Smith makes a cpl that would work for you, but be sure she can pull the trigger! BTW, for the years that our kids were not to be trusted, we kept a .38 special "snake" load as the first round to be fired from the cylinder, thinking that the first shot wouldn't be a fatal one and that if more were needed, adrenaline would get the 2nd through 6th ones fired if necessary.
Hope it works out for you...and thanks again for your service. We sleep safely at night because of your sacrifices. Rodfac