I deduct cost from deposits and if funds exhausted, I front the balance due pro's and make tenant pay storage to retrieve.In my highly litigious state (CA) it's essential to err on the side of caution because people will form attachments to things left behind, (including pets!)

There is a huge demand here on Long Island for vehicle storage. 

Only if its feasible that way people can type up their business plan and have it on the site for reference.

He fenced off the house, built a curb cut and drive way separately off of the road leading to the shop and he has been using it as his work/tool storage space.

I would start by researching and making sure that it's feasible.

He had basement storage, but tenants would fill them with tires, paint, and electronics and leave them there after move out.

Or simply having a high liability cap on our insurance is feasible.

I'm no attorney, but I'll take a risk and share what I think I'd do...I'd probably put all the valuables in storage for a few months, maybe a year.

I am evaluating the feasibility of investing in a condo that is over 30 years old and probably needs updating. 

Last time I checked into storage units into office it was $45000.