It's volume, not necessarily square footage, sounds like roughly 7000 cuft assuming 8 ft ceilings...big space. I'd rethink the ported (maybe a design that doubles as furniture or is it just the audio she's objecting to?). Two might work fine with nearfield placement, hard to know in advance. I tried two in mine at first, then three but was happier with four....no waf to contend with at all, tho....went sealed for ease of build and cab size to an extent, figured with enough of them it'd work