Long story short: I was cutting a hole for a new lightswitch, and I discovered a concealed junction box. And, as much as I was tempted to just patch that hole up and pretend I never saw it, unfortunately that's the only sensible location for the switch, so, I had to deal with it.
Now, I've opened up the hole, dealt with the junction box, and now I'm ready to patch it up. I opened up the hole so that the drywall insert will have sufficent thickness around the border to securely hold the box that is going to go into the spot, about a 1.5" border:
So, I could install the drywall patch, mud it up, make it nice and pretty, then cutout the box opening and proceed. However, the room for the electrical box will be kind of tight, so it will be tricky to precisely cut it out with all my measurement markings hidden by the mud.
So my question is: if I was to install the drywall patch with the cutout already in, will I be able to nicely mud the seams with the cutout there, or will that be a nightmare to, and I should do it the slower way?