Shame on you Matthew, you missed out THE most important warbird!
You confuse them with WAR Aircraft Replicas https://www.revolvy.com/page/War-Aircraft-Replicas-InternationalThese guys sell plans for a 2/3 scale P-51. Years ago I watched a fellow build one of thier FW-190's. Plywood fuse, foam blocks to fill out the shape with a VW engine. They had others like the F4U using the same basic construction but different shaped foam blocks and wing configurations.
That is true. But I still hope the OP won't be deterred. There is value in the design process even if the outcome is not what one expects at the outset. I think a "cartoon Mustang" would be a hoot even if it came in at 400 or 500 lb.
I actually considered something close to the FlyBike (sp?).Since we seem to be departing the reality of Part 103 how about making a silhouette P-51. A rollover could be contured to look like the canopy line, bent knees would allow the feet to be concealed by the silhouette of the radiator, (if the landing gear holds you might not break both legs.) A hopped up Olsen 65 for power and presto! Wear camo pants that match the paint job and it might pass the 100 yard eyeball test.
To me this makes as much sense as some of the ideals put forth. No not yours Pictsidhe.
Oh, oh, I forgot the air conditioning. Back to the drawing board.