Depreciating has reduced much of the income and probably just as big, I have put a lot of money back into my buildings to improve cosmetics and efficiency while modernizing them somewhat.

The agents that are willing to reduce their commission off the bat might not be the best fit.

Many applicants will offer to rent for a longer term hoping you'll reduce the rent or maybe you won't screen them as well.

I was thinking I'd be happy to reduce rent a little bit in return for setting up autopay but this seemed like a foreign concept to my prop manager. 

Sell the property after free equity (from appreciation) equals paid equity (DP) then split and roll the now all cash from equity into new properties where your equity is now at full value instead of reduced value. 

If you reduce the nightly price and are very open about the fact that it's not a (5-star) resort, then you'll likely attract a number of people that are looking to visit Hawaii on a budget.

We have put more money down on some of our recent purchases, but of course that reduced cash on hand.

I think the duplex is a bit too limiting on how much it'll help reduce your expenses and how much cash flow you can obtain.

We could probably scrape up the money to meet the 15-20% down but are there options that reduce the down payment?

The next step is to brainstorm how to increase your pay, or reduce your expenses.