David James in the UK has already done this, with tip tanks etc. The pic below is in our website gallery and David's description is:

"It's a Boomerang XL painted as SAAB J-21R, fitted with lights and wing-tip tanks (span increased to 100 inch (2540 mm)). Wren Super Sport. 2.25 l main tank, 0.5 l header tank. Duration 10 minutes plus. AUW (dry) 29 pounds (13.2 kg). "


Sara Parish
Wren Turbines