The lian li q07 could easily fit two hdd`s, one at the bottom and one where the optical drive would be.
Since you won`t need an atx psu, with a little creativity you could use the side vent along with a 12cm fan blowing on the board.
This is definitely doable in a Q07. The side vent fits with an ATX PSU's intake vent for 120mm fans, so a DIY fan mount here would be doable with some slim cable ties. Add some clothing elastic to suspend a 3.5 inch HDD in the optical drive bay and you'd be ready to go.