Quote from k1nsoo;1183886:
[video=youtube;CHSmV1_ZNP8]http://www.youtube.com/watch?v=CHSmV1_ZNP8[/video]
Puppeteers can hit Act 7: Climatic Crash three times if the person has an AoE pets that resets the knockdown gauge. Just simply summon those pets (preferably bone dragon) after the first hit.
So far the confirmed AoE pets are bone-dragon and pegasus pets.
When to summon pet is highly dependent on your connection. For example, I have to press my pet key slightly before I launch CC in order to triple crash. Some people who lives closer to server will have to summon a bit later, say during the crash.
And yes, MA solo is the best exp you can get in-game atm, given you use puppetry. The Only thing it loses to is 3x event + 2x combat pot in SWHM.