You give your opponents too much credit. Up to at least the $30 SnG level, your average heads up opponent will be neither smart enough nor aggressive enough to take advantage of the fact that you are quite obviously playing (and raising) with any two.

Additionally, you don't really need to worry about this against smarter, more aggressive opponents, anyway. They'll understand you're playing and raising with bad cards a lot of the time, but they'll also see that they have bad cards; and the frequent mix-ups in your play (raising with crap, limping with monsters, min-raising at times, pushing at others) will keep them off the scent. Against bad tight/passive opponents I don't even bother mixing it up, but against better players that's almost all you need to do.

To put it another way, if we start playing heads up with even stacks and significant blinds (say a BB of 1/20th of the average stack size, or higher), and you fold a couple early hands from the small blind, it's not going to give you the edge you seek. Quite the contrary - it means I'm going to start pushing you around immediately, and take a chip edge that you really can't afford to give away to a demonstrably more aggressive opponent. When you decide to get frisky later I may fold - or you may get frisky at exactly the wrong time. That's the beauty of establishing myself as the looser and more aggressive player early; it tends to result in some gorgeous collisions between a bluff from someone who's sick of my crap, and the first really good hand I've had.