You could build an XL wing and put it on an LEU, then I think you would be safe in upping the pilot weight. You should not try to lengthen the LEU wings because the spars are not as strong as the XL's. IMHO adding an extra bay at each end of an LEU wing would seriously stress the spars.
The XL wing was a big bux professional aeronautical engineer re-design. With proper stress analysis.
Unless Leonard has updated the folding wing plans, they don't cover the XL, only the LEU. Remember, the wing mounting setup is quite different between the two models. If you want to see an XL folding wing, look at ADCO Aviation's YouTube video series.
So it would be worth getting the plans for the folding XL wings and build new XL wings from scratch to replace the LEU wings?
Yes. Definitely...I'd call him to make the order, and let him know you want to use whatever you can take off the l.E. wing. He will have wise counsel for the "scrounging" operation. Nobody loves scrounging more than Leonard.