I followed homebuilts and the IAC for many years and there are alot of variations on these planes. The planes of today such as the EXTRA, SUKHOI, EDGE are relatively manufactured aircraft so they will be consistant. Now turn to the old aerobats and you will see quite a change. You have multiple wings designed for the laser alone, so which do you follow. The Pitts has been modified so many times you could conceive that any wing length or chord will fit the rule. If these planes are one off how do you prove it fits the rule. What if I take the fuse of one plane, use the wing of another, and the tail feathers of two others (same basic airplane design. ie pitts, laser etc). Technicaly this would be a laser however simply using the mods of different lasers built over the years.
I have plans for a 33% eagle I am finishing up that will not have eagle wings or tail feathers, only cowl and fuse. There is a full scale with the same outline (highly modified) but will I get complaints if I try to fly in IMAC? It is 10% I will have pictures to show general outline but is it a true eagle within the scope of IMAC?
Well thats next year anyhow.

Oh yea another good design is the POGO plans by Joe Farris. It has a nice outline and I think with the right reshaping of the tail feathers it would be a nice performer (not to mention stable).

Good Luck
V-Snap