Visit your local codes office to determine what the minimal allowable roof slope may be and approach some architects to see if perhaps they might have another idea. Spending 60K+ is a situation where you want experienced licensed local professionals to give you their input. You won't get any but the most generic of suggestions online.

I hope this 160 square feet does not cost 60K+.
Do you really think that $375+/sq ft is going
to be the cost of an addition like this?