It can be easily accessed with a small folding step-stool that can be stored in a lower cab... most modulars offer them as an accessory.Leaving a big gap between the top of the uppers and the ceiling creates a dust-collecting, hard to clean area.

The problem was that tenants would fail to return all their keys so I had to go to the store to get a new key made.

The Bigger Pockets book store if full of great books: https://www.biggerpockets.com/store

Also, where would I store them?

Is it generally better to order materials through a big box store (i.e.

@Jack BeachJust tossing ideas - Is it big enough for a gas station and a convenience store?  

Go to a plumbing supply store.

basically job stabilityWhat kind of future commercial development is coming in - new malls/shops/etcAlso proximity to food/restaurants/shopping/etcNot near any flood zones/major rivers/ loud train tracks/minimal liquor stores

The Bigger Pockets book store if full of great books: https://www.biggerpockets.com/store

.  The retail store has a lease that expires in 4 years and is paying ~$2,000/month.