Since the plan is to be able to sell or rent the two homes separately at some point, I'm going to have to divide the lot for the container house project.  The garage has to go, and that will leave the main house with less property, and more urgenty, less storage.

First, I had thought to build a small shed at the east end of the main house, for bikes and yard tools.  My mom made the excellent points, though, that we don't want the lot to look crowded, and putting a shed by the patio will block one of the few remaining planting beds.  Even my idea to have a storage container partially hidden behind the demolished garage won't do: still too much visual obstruction, and it's on the back lot so it won't belong to the main house.

What to do?  Revive my porch idea!  I had mostly abandoned rebuilding the old house's front porch, but a variation on the layout could yield a small storage shed, while dressing up the house significantly.  My plan is to build a slightly wider porch with a small roof gable in the middle, and flank both sides with arbor stickwork (similar to this picture).  The covered porch would have solid side railings with siding, and on the north side, I'd widen the railing to about 3 feet.  That section would end up about 5 feet off the ground, so that with an access door on the side, it becomes a tiny shed underneath, big enough for a few bicycles.

Granted, this will probably wait until next summer, after the main house is built.  In the meantime, bicycles and yard tools can live in the basement.  I'll help clear out extra junk down there and in the garage before demolition.  This shed idea will be nice, though, so my folks won't have to cart all their outdoor gear up and down the basement stairs.