To get yourself some more space, it can be helpful to remove the existing box and replace it with a larger one with more outlets (remove 1-gang, put in 2-gang). You'll have a lot more work to do, but I find it easier to fit the extra connections. Plus you will have an extra large hole to push wires to the outside wall. Caulk and/or spray foam the gaps to prevent outside air infiltration!
With an old work 2-gang box, you still won't have to do any drywall repair. Rough drywall and paint edges will be hidden behind the wall plate.
Are you planning to surface-mount the exterior box, or recess it into the wall?
Surface mount is way easier, but somewhat ugly. If you are recessing, you can offset them by a couple of inches so they don't back into eachother.