I've only found a few layouts that "3-dot" everyone (which would be a 7.0x multiplier), but getting at least a 6.5x is possible on every grid, depending on what starting inventory you have. And as long as you 2-dot someone, their Happiness doesn't go down much (4 points max, less if they get happiness from activities or perks).
It doesn't really matter that much if you 2-dot MC, by the way. His happiness is so low that each Need you meet barely gives you any points. You're actually better off in many cases keeping him at 2 dots and meeting other DIKs needs instead (assuming you keep the same or better overall multiplier).
Some example layouts are in the link from my post earlier:
