Looks like you have a good handle on things. I don't really have any suggestions as it looks like you're on the right track. Just a matter of doing it how you want it to look. You could move the winch out a bit further if you didn't want to cut the grille.
Years ago I fabricated a front grille guard from scratch for a solid-axle Toyota truck. I tried to make it look 'Humvee-like', with a center section and surrounds around the headlights. I made the main center-section stout enough I could hang a conventional Western snow plow on it, but not overly heavy built ...to conserve weight on a light Toyota. I used it for plowing snow for several years. Never came close to tweaking the mount.
I fabb'd the plow hydraulics' mount section of the grille-guard such that the plow lift ram could be removed from the grille guard, and a winch plate (and winch) put in place (during the summer). I'll have to look and see if I can find a picture of it on an old hard drive.
It would be a lot easier to do something similar on a Hummer the way the front of the frame terminates at the front.
I like where you're going with yours.