The firm's fee will probably eat 1/4 to 1/3 of your savings.

They do not always.....sometimes people have to eat some of the cleaning fees to avoid turning off guests. 

That means not traveling unless necessary, less going out to eat/drinking and avoiding unnecessary expenses of all types till your HELOC and CC debt is close to nothing.

If that means a second job or eating noodles every night, so be it. 

I would agree that the best way to manage this situation is to forgive any late fee incurred and eat the NSF fee as well this one time.  

It’s all about finding a balance that works for everyone involved.Regarding closing with short-term private money, it’s an option, but you’d want to weigh the costs and ensure that it doesn’t eat into your profits too much.

Once you transition one of the homes into a full time rental you will reap that benefit by filing a schedule E at the end of the year.There are a few loopholes to consider like calling one home a "Vacation/Second home" which allows you to pull out 80% LTV with a better rate. 

. - if you need two stairwells and an elevator, that will of course drive costs way up and it also eats into your floor plate area and can crush layouts on a smaller building, possibly turning your small CMX2.5 lot you'd planned to build 5 stories on into what may as well be a CMX2 lot and allow only 3 stories, since you can't actually fit 2 stairwells, an elevator, a hallway all the way through from front to rear, a small lobby, a mail room, etc.

When you go out to eat and have a nice meal and great service, do you stiff your waiter/waitress too? 

I can say that self-managing a STR from afar is beyond me (no experience as a property manager) so that would eat into cash flow.