I do this because as a investor I expect a minimum 10% return on my money and since it your equity that is actually creating cash flow as opposed to the property it would be negligent of a investor to not attribute a return to that money.

Contact banks and see what additional loans they can offer with lower down. 

You can pour an additional $100k into the property's principle in year 1 but that equity won't do you any good unless you refi, sell, or take out a HELOC (i.e. your monthly payments will be unchanged)... make your money work while you do, invest elsewhere 

With mine, I ended up paying the PM company additional money every month because somehow their expenses exceeded the rent collected.

I like this idea, but not all syndicators are willing to do this.Partnering would probably be a good idea as well; finding someone with experience who needs additional funding for projects.

If they won’t do that I let them know they may be subject to additional costs for collections, and that will hurt their future prospects for rentals as well as other credit based opportunities. 

I see so many room illegal additions/conversions where the homeowner spends a lot of money on the project, but when they sell the appraiser assigns it no value because the square footage is unpermitted.

There is no one single way to invest in real estate and networking with many different investors may give you additional ideas for achieving your goals.

However, the only thing you have left out of your post is if you are sure you have the extra capacity (with respect to amps) in your panel to run an additional 33+ amps. 

I have an addition I’m having done in my personal residence by one of the best contractors around and he’s on month ten now and still not done .