[john70t]

The stage is facing and functional to only half the room, so you might want to think of going from there.
Divide the areas.

Usually people expect band sound to be originating from directly in front of them.
More watts for that half the room, but a few more speakers in back for those sitting and eating far away.
Not everyone want to sit and quietly eat right in front of a subwoofer.

Muti-use-capability is better for rent-ability.

That room will create weird echos and bad sound effects at high volume.
There are two open roof lines for sound travel.
Some sound deadening panels might help at the ends.
The speakers need to be at an angle.

I don't know how many separate and tune-able channels that would require...6 or 8 perhaps.