What's the rush with a simple engine failure? It is not a situation where you have to land back immediately, in fact you might have to use a take off alternate due to performance issues, low vis doesn't matter anymore with OEI CAT IIIa certification in the 737. On the other hand flying around with flaps 25 (which is a normal take off flaps setting) just because i do not like to bring the flaps up from take off setting seems rather stupid as well.
However in any situation requiring immediate return simply use the Immediate Landing Checklist on Back Cover 1 in the QRH which does not require to raise the flaps.