Time to practice the recipe for a long and happy relationship: "Yes, dear."

It's reasonable to make sure the outbuilding in which the bikes will be kept is weatherproof (to keep the salt out) and secure (to keep the bikes in and unsavory types out). IMHO this would rule out any prefab garden sheds. If you've got seven bikes (plus hers), you could also ask to have the storage location air conditioned so you don't have a heat stroke while working on the bikes.

All this assumes, of course, the lady is more important to you than bikes in the dining room.