I hate sounding like a broken record but go to
www.thesmokering.com
That site is alot lke this one, full of .......
people with alot of expirence and knowledge about their hobby. Theres guys on there that build huge trailer mounted smokers, 50 gal drum smokers, one guy even used a computer server housing. Turning an oven into a smoker actually sounds like a good idea being its insulated and will hold some heat reducing the amount of fuel you would use and help hold a consistant temp. Keep us up to date if you try it.