Almost like a proto-Earth - Thea collision.
That would probably work, but instead of forming a belt, could form a nice hot planet with iron core and perhaps a moon.
When it's in the debris phase, all those little chunks would have more surface area to release volatiles. It'd be one hell of of comet for a while.
I'm more of the opinion to freeze it out. The last thing we need at this stage is to add more heat to the system.
Fire and Ice
Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
-- Robert Frost