Hey @Guang Yang, no need to use any kind of extra stuff for a single unit like @Patricia Andriolo-Bull said.Just use the built in tools on VRBO and AirBNB and you will do just fine.

The only question is if the increased risk of loss is worth the extra return. 

I have also run the scenario of putting extra principle payments into the conventional mortgage, but we cannot put away as much, because we have to bank for large purchases down the road.This spreadsheet takes into account that my wife takes a drop in income in the next few years to care for babies (growing family), also factors in major expenses on the rental property, and assumes that we have 10% rate on the HELOC to be conservative. 

Buy a sofa and keep the sofa bed to keep the extra-capacity, at the risk of cluttering the living room too much?

Quote from @Sarah Hartstein: Hello everyone, I am brand new to this website and looking forward to gaining some extra insights on property within the US and beyond ;) I started as a part-time Realtor with Keller Williams in Santa Barbara, California, however domestic sales never really “tooted my horn.”

What some companies do and maybe something you should try is setting up a split payment schedule for them but for a fee and make a little extra scratch. - if you do this make sure it is well documented so that your eviction will not skip a beat if something goes wrong. 

You want to work with private money, not residential mortgage companies for investment properties.

So if you can do just a few deals a year you can be making some extra money, learning, and establishing yourself so that eventually you can easily transition into being full time.

I know that there are some extra requirements of the USDA loan like the property needing to be in move-in ready condition, but assuming I would be looking at move-in ready properties, are there any other hurdles I am overlooking in using USDA financing? 

I used a hard money loan to purchase this off market deal.I rehabbed the upper two units within two and a half weeks and have a renter already lined up for one unit.