The wording of the current Strava rules doesn't seem to unambiguously rule out recumbents, so there's the big gain. And if you're currently wearing baggy street clothes, switching to cycling clothes would probably be bigger that just about any straight component upgrade that you could do to a road bike.

I would say... if you wear a skinsuit while riding a recumbent in a paceline with a tailwind, that 5mph gain you're looking for should be no problem.