That's generally something you do at the end of your life/investing career when you have all the income you could want and are just looking for places to stash cash outside of a .25 APR savings account.

The more you buy at the high end margin the more reserves you need to have stashed away!  

At least if you live in one unit the tenants rent covers all the bills and you can stash away more funds.

I would just be concerned with having very little cash flow if I didn’t have a nice stash of cash for unexpected stuff.   

No pension, no 401k, no IRA , no secret stash under the bed . 

If you can make a quick 40k Id consider that because then you can use that as a downpayment on another rental without going into your current cash stash.

Assuming you are both working, you should be able to continue saving.You will still have cash in your pockets and you will have flexibility to try and rent the current home for additional cashflow, or simply sell outright and get more capital to add to your stash.

I’m currently stashing as much of my income as possible in order to come up with a down payment for my second investment property which, like my first one, will likely be a house hack. 

Are you sitting on a stash of coin you're itching to plow into a different investment?

Stash that cash, CS students get paid absurd amounts in big tech internships.5) Graduate with little to no debt, with the best technical skill a person can have today. 6) Work for 2-4 years at a tier 1 or 2 tech company.