There is also a possibility to purchase additional acres for building. 

A roll-away center island might help with storage and give additional working counter space.

I agree with those who hinted that you'd be wasting your money if you put your own money into accelerating your mortgage payoff, when those same dollars should be going towards additional investing.I'll repeat Joe's point: don't help your tenants pay for the properties you already "own"!

I would love to help you with the bigger projects only (additions and larger).

In addition, I would recommend: Listening to the BP Real Estate podcast https://www.biggerpockets.com/podcastListening to the BP money podcast https://www.biggerpockets.com/moneyshowAttend your local REIA meetings to networkStart analyzing deals to get practiceEngage more on the BP forumsAll the best!

One of my favorite quotes by Jim Rohn is, "Your level of success will seldom exceed your level of personal development". 

The question is whether or not the benefit of getting the third property without any additional cash out of pocket is worth increasing our debt. 

In addition, attend REIA meetings and study.

Even if you engage a broker, you should still shop around an additional couple lenders yourself (if you have the time/energy).Freddie SBL loans cap at 50 units, so you won't be able to take advantage of that program (unless they can somehow make an exception), but there are still great Agency (Fannie/Freddie) programs that would work. 

It will take talking to a lot of community banks if you don't have additional funds to showcase liquidity reserves and a higher net worth, as the loan will be full recourse.Partner up - combine your equity with a couple other investors to have 30% equity ready for that $1 Million property. - Tim