I do very little in Photoshop, and when I need to do more (retouching for example), it's easy to keep track of things because I don't do it often at all.
OK, fine, actually sounds like a good way to work if you charge by the hour.

And photos where I have to do retouching, with skintones, are ok in sRGB anyway - stuff is in-gamut.
You know this because you render to a larger color space and plot
every image color gamut in 3D then decide to use sRGB?
Of you render in sRGB and just hope or assume nothing is clipped that could be output (on print** or on the web for those with wide gamut displays). Or you simply don't care. That's fine. Some of us do care.
I only use Adobe RGB when I have to print something as I was saying.
Print to what? You do agree that there are lots and lots of printers who's output color space greatly exceed Adobe RGB (1998), right?
I think things are moving towards Display P3 to replace sRGB, not Adobe RGB.
The differences in color gamut between DCI-P3 and Adobe RGB (1998) are tiny.
Yes, it is WYSIWYG, and it's what I use when printing.
You believe that the color gamut of sRGB (or any RGB Working Space) and an printer output color space are even close to matching or allowing a fit?
Do you realize that NO printer can output all of the sRGB gamut? None. I'd be happy to plot 3D any printer color space you can supply, or I'll supply one or more, to show you this fact.
SpectraView doens't have a Display P3 target for comparison's sake.
You simply need to plug in the aim points (targets for calibration) to get close. I would be happy to show you or better, I can build such a target in SpectraView, upload and you can load it directly for this task.
I don't think it is at all necessary but, your call.
unless I can have a monitor that does 100% ProPhoto RGB,
That will never happen,
never. It is impossible. We can go there if you wish. Again, the very concept of color management and image editing is that the display and the Working Space are divorced by design.
There is no reason why, people who wish to output data they can capture and output but can't fully see on a display cannot do so.
You have an option:
1. Funnel all your image data into a color space you can display while clipping colors you can capture and can output but not do so or...
2. Keep all that color data, edit carefully in a few areas where you could alter color you can't see (but can 'measure' using an info palette) and use that color for output.
Your choice of course. I prefer to keep and use all the color and data I can get.
When I shot professionally, and the job required (at time) 4x5 or 8x10 film, I wouldn't think of shooting that format then cropping down to a medium format size or less. I no more would render into anything but ProPhoto RGB from raw, or do so only in 8-bits per color, or resample the pixels down from the native capture. But that's just me. Well not just me....

How do ACR/LR use the monitor profile?
Exactly like Photoshop and every other color managed application. Examine the color space of the data (and in LR, that differs depending on the module!). Examine the color space of the display as provided by the display profile. Use Display Using Monitor Compensation as described in the PDF.
** T
he benefits of wide gamut working spaces on printed output:
This three part, 32 minute video covers why a wide gamut RGB working space like ProPhoto RGB can produce superior quality output to print.
Part 1 discusses how the supplied Gamut Test File was created and shows two prints output to an Epson 3880 using ProPhoto RGB and sRGB, how the deficiencies of sRGB gamut affects final output quality. Part 1 discusses what to look for on your own prints in terms of better color output. It also covers Photoshop’s Assign Profile command and how wide gamut spaces mishandled produce dull or over saturated colors due to user error.
Part 2 goes into detail about how to print two versions of the properly converted Gamut Test File file in Photoshop using Photoshop’s Print command to correctly setup the test files for output. It covers the Convert to Profile command for preparing test files for output to a lab.
Part 3 goes into color theory and illustrates why a wide gamut space produces not only move vibrant and saturated color but detail and color separation compared to a small gamut working space like sRGB.
High Resolution Video: http://digitaldog.net/files/WideGamutPrintVideo.mov
Low Resolution (YouTube): https://www.youtube.com/watch?v=vLlr7wpAZKs&feature=youtu.be
Still true, but to a lesser degree with Adobe RGB (1998) than sRGB. And again, I've shown how using a smaller color gamut editing space for print produces those '
blobs' of color which again, were plotted in an output color space to a somewhat modern inkjet printer:
http://www.digitaldog.net/files/sRGBvsPro3DPlot_Granger.tif