GFI bathroom wiring

Eliminate the existing GFI outlet by cutting the wire at the next GFI outlet back in the circuit. Then run a whole new 20-amp circuit from the panel to your 3 new GFI outlets.
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I am trying to add a few GFI outlets to my wife's bathroom. I also have to move one of the outlets because of a larger mirror that I will be installing to make wife and daughter happy.
The problem is, I know it is against code to put a junction box inside the wall. And I think leaving it outside will cause my framed mirror to not sit flat.
I spent all weekend trying to track down wires. I figured out the entire breaker is dedicated to the bathroom GFI's only. I have only 3 outlets currently on this entire 20 amp circuit.
The power goes to the outlet I want to move from above in the attic. However, from this outlet it goes to two other bathrooms and I cant find the wires that branch the outlets together. I am guessing it is through the studs when they built the house and as such, they may be inaccessible or if they do go into the attic are covered under the floor of my bonus room to which I have no access because the bonus room is finished.
As I see it I have two options:
1. somehow leave the current outlet and make it into a junction box and somehow recess a new box so that the acess cover would be flush with the wall. Then run a wire from this box into the crawl space then to the two new outlets in the bathroom.
2. Maybe more work but a more proper solution would be to install a junction box in the attic where the current feed is to the existing outlet, run a wire from this junction box down the entire length of the wall into the crawl space. Install another junction box in the crawl space and make the connection to the new outlets here. I would also have to run new wires from the two other outlets in the two other bathrooms into the crawl space to tie into the junction box. (Doing it this way requires new wiring on the entire circuit but eliminates an accessible junction box being required in the wall).
One thing I wondered. This is a GFI circuit. The breaker is not GFI but the outlets are. If I have connections in the crawl space where sometimes there is a little moisture after a lot of rain, will I have trouble with the GFI tripping? My idea would be to use one of those outside metal moisture proof boxes but just run regular 12/2 wire to this junction. Would using conduit to this junction be a better idea?
Any help is appreciated!

Plan 3 Have a glass guy cut a hole in the mirror and use a mirrored receptacle cover.

Having a hard time understanding this. The outlet I want to eliminate is the first outlet on the circuit.

Sorry I took it as being wired as the last outlet because you didn't mention any splices being in the outlet box. What about running a new wire to the next existing GFI thus refeeding it?

because of the mirror. Inside that outlet is the wire that goes to another bathroom, etc. I can re feed the outlet but that does not solve the problem of the outlet being in the way.

e because of the mirror. Inside that outlet is the wire that goes to anothe r bathroom, etc. I can re feed the outlet but that does not solve the probl em of the outlet being in the way. Sorry, I re read your post. You mean re feeding the next outlet in line. I can do that but to tie into the existing breaker I would have to come in th rough the top in the attic.
One thing I am wondering. My breaker is 20 amp gfi. Is this pushing the lim its for two hairdryers at the same time?

You cannot run 2 hairdryers on the same 20-amp circuit at the same time. A 20-amp circuit can handle an absolute maximum wattage of 2400. Most hairdryers are 1600-1800 watts each. So that means you'll be trying to run anywhere from 3200-3600 watts on a 2400 watt circuit. You're better off running an extra circuit. Curling irons only add to that load.

That is right but not accurate. Two are too much for one circuit for sur. The rating is just BS Hair dryers are more like 1400-1500, no matter what they say on the label. I tested a bunch of them and this was the most current draw. Some that called themselves 1600w were more like 1200w.

I guess the same rules apply to hair dryer ratings as air compressors and blenders. Write anything you want on the box.