That's HIGHLY suspect. First of all, if any of you have ever assembled an L-4, let me tell you, it's impossible for one man to do and even with help it's going to take the better part of a day to do. He would have had to have a bunch of tools including a torque wrench, safety wire, wrenches, etc. Hell it would take him at least 2 hours just to get the wing root fairings in place and that's if he had a ladder to get up there and put them on!
You can't fit an L-4 fuselage into a CG-4 without pulling the gear, which means he has to have jacks to attach them, then he has to fill and bleed the brakes.
Then he has to run the cables and tension them, safety the turnbuckles, then hook up the airspeed indicator, mount and wire the prop-man I tell you its not like the story said- he assembled the airplane and took off. Yeah like he changed a tire and off he went.
I'm not certain you can even fit an L-4 wing in a CG-4. If you can it would take one for each wing and one for the fuselage. That sounds a lot like a war story to me.