Flaps add both lift and drag. While they slow a plane down when fully deployed, as light as the wing loading on the big Rascal is, they would likely keep the plane floating. Spoilers just kill lift, and deploy upwards, usually on top of the wing, but you can program "spoilerons" and make the ailerons work as spoilers. Some notable aircraft use spoilers instead of ailerons, the B-52 being one of them. Unless you just want to play with things, why complicate a great airplane , plus to add flaps would require some major reconstruction of the wing, recovering, etc.