4x48 T5's would work although 12" isn't that deep so you could keep them up a little higher.
I have a 10 yr old SPS tank that has always been T5's and not only have I never changed bulbs at 6-8 months but I don't recall anyone ever recommending that frequency (except maybe an LED user) - but what do I know.
I spend $80 on salt twice a year.
I spend $80 on RODI water twice a year .
I spend $80 on frags every month.
I spend $80 on test kits and other doo dads every month.
I spend $80 on T5 bulbs every 18 months.
. . . But that's the kind of guy I am. LOL.
-Mike