Bottom line, listen to the side of you that is reminding you this is a business.

It depends on the box size, where it is at location wise and demographics, site lines, access with cross traffic, and if dark but current tenant still paying or totally vacant.Smaller box sizes usually have a long list of tenants waiting to go into the spaces in strong markets.

If he does get the next investment property in his name, how would we get the next and the next if we just rely on our own personal line of credit with no money down...?

Basically they are in backup position, pay for all due diligence, get everything lined up and at any moment you can take another offer.

You will have to hire a securities attorney to work with and guide you through the legal structure as well as the legalities of the capital raise.Bottom line, it's totally possible to raise the funds, but you need to have the right structure in place and a track record to support it.

There are hard water line stains on the cinder blocks indicating flooding has been an issue before.

It's just a bit cost prohibitive on smaller properties, and the IRS doesn't mind if you just do it the easy way (the incorrect way) and use straight-line depreciation since that results in overpaying taxes. 

I thought I would add a line in their lease extension, due in December, that it could be assigned in the future.

So the big question I have is do any fellow landlords out there use any type of app or program for your phone that allows you to set up a sort of "Mock" business line.

It can and will be thousands of dollars, and you must consider this when looking at your bottom line.