So I talked with SG and apparently if you can't make enough legal decks, you're forces to make illegal ones and auto lose. So this strategy wouldn't work (that's what SG told me, though I get the feeling it's because I pointed out the problem and made this the solution).
Not that it matters, but you wouldn't have to lose air cards every round if you made a deck with 18 air cards and 18 other cards. You discard the 18 other cards along with 12 air pendulums/pillars, convert 12 more pendulums/pillars and continue on as before. So you could go on as long as you had the total cards to keep losing without ever going down in total air cards.
It's a moot point though, so everyone just continue on as before.