Any chance you can run new lines, including drain, inside cabinets way towards the back? Tie new sink drain into present location. Hide them behind a false back with enough ventilation to let room air in. Extend new drain a bit past sink with a 45 el on end to outside so you can have a clean out to run snake through.
If what i laughingly call my brain remembers right, the vent needs to be within 6 feet of sink drain, so you may have to run that up inside wall. Possibly even run vent outside exterior wall inside a chase. Two decorative chases on each side of window over sink masquerading as pilasters or columns? Clean out acess hidden in one chase behid access door/
You could furr out studs to get thicker wall, insulate real good and run new water lines on room side of insulation. but that could be a bit risky, considering your winter temps.
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[CENTER][FONT=Comic Sans MS]Look at the nail, not the hammer. Watch the fence, not the blade.[/FONT][/CENTER]
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