Is it possible to reach the maximum armor rating with just the main armor piece and the boots?

Doubtful, as the Matched Set Perks are a big help to reaching the cap. You could get close depending on material, exploits, crafting skills and some Alchemy. You could certainly get it high enough to be effective in the game for your character.

Did you ever see this thread: http://www.gamesas.com/topic/1300996-armor-cap-ridiculous-damage-enchanting-alchemy-smithing-only-21-perks-thread-5/

Start with the first one that is listed in the OP. I remember when these threads first started.. I was in awe of the geekdom being displayed. Still am, I suppose.

Makes me think it might be possible to hit the cap with two pieces. But, I think CCNA's comment of "high enough" pretty much says it, anyway.