You'll have an easier time if you don't stick to the "All-grain" portion and instead just keep stepping it up with Dry malt extract mixed in a bit of water and boiled to sanitize.
Anyway current commercial recordholder is Sam Adams with Utopias at 24% Abv. I don't think it is a lager.
Realbeer.com: Beer Break - Sam Adams Brews Strongest Beer Ever
"People should not be afraid of their governments. Governments should be afraid of their people." - V
Secondary: Shady Lord RIS, Water to Barleywine, Pumpkin wine, burnt mead
Kegged: Crappy infected mild
Bottles: Apfelwein, 999 Barleywine, Oatmeal Stout, Robust Porter, Robust smoked porter, Simcoe Smash