Sure it's possible. Just use decent/good builds and make sure the real players don't fail at the game too much and you should be just fine.
I've done it with 2 guildies and 5 heroes. If I remember correctly this was our setup:
me as a Dslash Sy spamming warrior
ele guildie with ursan..
necro guildie SS/anti-melee(SS, barbs, mop, enfeebling blood, enchantment removal, ... )
2x hybrid monks (both with aegis)
1x mind blast ele with some wards and enchantment removal
1x ritualist with splinter weapon, ancestor's rage, .. and frozen soil (secondary ranger)
1x MM with virulence + epidemic
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