I also am a landlord of 2 rental properties and plan to continue expanding my portfolio.

Ground up storage development has its upside but my unsolicited recommendation would be to look hard for an existing facility that you can expand.

If it is to expand your real estate portfolio, I'd hold on to it. 

I stacked hay, drove tractor, balers, seeders, and other farm implements, broke horses, trained race horses, jockeyed, trimmed trees, shoveled snow, worked at several gas stations, painted houses, painted coal dredges, security guard, roto tilled yards, planted flowers and gardens for folks, raked leaves/yardwork, eventually worked oil field when it was booming, even crawled in tunnels installing coaxial cables and fiber optics, loaded explosives in seismic testing holes, eventually a lawyer, and landlord. 

Most lenders want to see that you take good care of your rental assets and put your cash flow back in to keeping the property up to speed.One last thing, if those properties are on separate lots, separate legal descriptions, you have expanded options and more options that what I just told you 

We had a small team of 4-5 for many years, then expanded when I came back in 2015.

Something fairly affordable (or at least worth the money) would be preferred but any feedback would be great.I have a few duplexes in Detroit that I rent out but looking to expand my knowledge and my portfolio. 

I am looking for feedback because while I have a couple good private lenders, they have particular focuses and aren't always liquid, therefore I'm looking to expand my data base.

A lot of gas station brands are looking to expand use, so that could help, though it would likely require some parking. 

Although this will be way down the line, assuming all goes well, I would eventually like to expand into additional multi-families and eventually get into commercial real estate or looking into expanding my reach outside of the surrounding Columbus area.With all of this being said, I welcome all advice and help pointing me in the right direction.