ahh oaky metal ceiling, that walls are bricK? wood?drywall? i would run a Thick chain,nylon rope, or hell hemp rope(my girl has tons of the shit) and large hooks from across the walls to hang reflectors and bulbs. yout setup for the fan should be fine maybe replace the plastic piece with metal shelves instead,
but yeah remove the ducting and put the fan on the filter so long as both air ports on the fan are covered and its secured o the filter so as to not rattle your noise level should stay about the same.