Remember that you can still put commercial engines on military designs. So if speed is not of concern and you want to be as fuel economical as possible and not worry about engine maintenance (after sensors, engines are second most common MSP-guzzlers), go ahead with one or two 50 HS commercial engines on your carrier. After all, the fighters do all the work, right? If you also have a separate dedicated sensor ship, there's almost nothing breakable on the carrier itself. CIWS, magazines, crew quarters, hangars, fuel storage - I've never seen them break.