What is the interest rate on that and the furniture payment.

For mortgage debt, the following additional requirements must be met:the party making the payments is obligated on the mortgage debt,there are no delinquencies in the most recent 12 months, andthe borrower is not using rental income from the applicable property to qualify.

While I am not an accountant, and you should speak to yours about this, there is a loophole in the tax code called the STR Loophole which allows your STR (provided you are not using a PM) to be counted as active income/active expense so that the costs, payments, depreciation etc. goes against your active W-2 income.

Take a look at AirDNA, the enemy method, STR Insights to get a better idea. 

I get a judgement and execution and contact the local constable.After a month or two, if they don't pay they get summonsed to a payment hearing.If they don't show, now the constable threatens to arrest them if they don't pay.Just collected 5k judgement doing this.Good luck

Average Houses are around 600k where I am living which means if I put 20% down I’ll be looking at a payment around 4500$.

The cons - very hard to cash flow off the bat, especially with a low down payment and...

., if the housemate who’s leaving was covering 75% of your mortgage payment, that could be a major problem…but if they were only covering a small portion of the mortgage and/or they’re easily replaceable, it might not be much of an issue).Moderately important: anticipate and manage your relationship with the housemate tenants.

Another option is to get an interest only loan, which reduces the payment amount and thus allows for more cashflow.

So a big monthly payment you're thinking?