Well, you can use what you suggest, but it's a really clunky, and frankly ineffective, way to deal with movement.

For 1, you can't sustain movement with CtM, so you can't spread out further if you need to unless you resend the ; and make them CtM again, which can further exacerbate the issues below.

Second, it is going to rely wholly on the mouse position vs slave posistion. If your mouse is over an area they can't click, then they won't be able to move. This means mobs with large hitboxes or anything else that clips the clickable area, like terrain, walls, other toons etc will prevent one or more toons from moving. Or in the case of unit frames and Rightclick, could end up causing you to open menus or even triggering macros unintentionally instead of moving.

Third, Click to Move always uses a "run forward" command to get to the location selected, meaning any toon moving in a direction not directly forward will end up facing the wrong direction because they have to turn to face the destination of the click.

In the end, this gives you very little control of positioning and there's the added detriment that sometimes you will see performance drops as the mouse moves from window to window as the FPS raises and drops on each screen which can, in times of high spamming, lead to your mouse getting stuck on a slave screen instead of returning properly to the main window. It may not be a normal occurance, but it does happen.

Now, as far as the S&G aspect, yes, it can be done. I'm not sure how your scaling works out for your setup, for mine it was too much variation so I had to readjust the numbers. All you need to do is add a second <ClickMouse RButton> without any other parameters to actually get the click to process.

Code:
<Hotkey ScrollLockOn Oem1>
    <SendLabel w2>
        <ClickMouse RButton Window 20% 20%>
			<ClickMouse RButton>
    <SendLabel w3>
        <ClickMouse RButton Window 22% 22%>
			<ClickMouse RButton>
    <SendLabel w4>
        <ClickMouse RButton Window 18% 18%>
			<ClickMouse RButton>
    <SendLabel w5>
        <ClickMouse RButton Window 20% 22%>
			<ClickMouse RButton>
I did try several different variations of the concept, but nothing I could think of worked any better.