Someone asked me if the Imitation was profile-legal. I'm not sure how I came to be an expert (maybe just because I can't keep my mouth shut?) but here's the NW Profile rules as pertains to the Imitation. Note that profile is not a national event -- your rules may vary, so make sure to check.
3. Airplane: Any profile airplane is allowed.
3.1. The engine may be mounted in any configuration -- side-mounted, upright or inverted.
3.2. Doublers or triplers and cheek cowls are allowed, including faired spinners, but the fuselage must meet the "profile" definition of maximum 3/4" thickness by the trailing edge of the wing/flap hinge line, and the engine must be fully exposed from lugs to plug.
4. Engine: Any engine up to 15cc/.91cu.in. Electrics allowed per AMA Stunt Rules.
3: Yup.
3.1: Yup.
3.2: Yup, yup, yup (1/2 inch, not 3/4 inch), and yup (in fact the engine is fully exposed in the 'real' Imitation)
4: Yup.
Were I going to build one (and oh, man, am I tempted!) I might swiss-cheese the fuselage and laminate on some 3/32" balsa sides, or make a BIG cutout, fill it with foam, and ditto the balsa sides. This should be far more rigid, and lighter to boot -- if you don't take the weight of glue into account. Cover the outside with silkspan or CF veil, and it should make a nice rigid assembly.
Note that it's a lot more work, so it turns a "knock it out quick" project into something longer.
Note, too, that this may not be legal in your area -- I understand that 1/2" wide behind the wing is the limit in some places.
Finally, note that it's also not wise at all if you're still Sir Crashalot of the Knights of the Round Circle, because a cool laminated fuselage is way, way harder to repair than a solid hunk of wood. If you fly Profile because you're not world class but are too good for Advanced, and you just NEED some trophies, then it's probably worthwhile.