Use a Cline reg and put the fuel tanks in the tail if you like. It would add about 1 ounce of weight to the plane. The Cline works great with 2 strokes but you need to tap into the back plate to get crank case pressure (usually very easy). The reg must be within 1 inch of the carb barrel, it doesn't matter about the mixture needle. Three lines work great, carb, fill and pressure relief.

Carl