I have 3 windows as well that don't stay in the open position that I have to replace.

They would be putting in some money and their service as sweat equity, and we would be putting up money and my wife’s services. 

The HELOC would act as en emergency way to tap into their equity if needed - as long as they don't spend it unwisely!

I’m not looking for a step-by-step guide, but I know I’m not the only one in this position.

Right now you may see them as less than suitable for partnering with, Maybe rethinking your own position about making money with them might produce a profit.

With the equity you’d free up, paying off $50k in personal debt and boosting your credit score while freeing up $3k/month sounds like it could significantly lower your stress and open doors for future projects.That said, selling means you’d lose a cash-flowing asset, even if it’s not huge.

We bought it for $399k, and it’s now worth about $650k with $250k equity.

(This includes Amazon)Equity Loan The last opportunity I've thought about recently, is taking the equity out of the house here in Italy, and investing it into a property in the US where appreciation is higher.

There is almost no scenario where a condo would ever positive cash flow while servicing debt, and very little positive cash flow with no debt.If your budget only allows for a condo, find a better place to put your money to work.   

If it is a credit/equity line, you could provide a lender letter that the funds are available immediately for funding - and cured any recission period.