Some banks only use one bureau like Transunion or Equifax and whatever that score is they will use to qualify.My advice is to look into a cash out refinance first before you apply for the Heloc so you can pay off debts through the refinance process.Another option would be a personal loan where the bank pays off your debts by consolidating them to help you free up your DTI. 

What are options for payment for landlord?

Also, since the unleveraged returns in Puerto Vallarta are (significantly) higher than in most places in North America, you don't need the lending conditions to be as good to get an equivalent return.Many North Americans have a third option, which is to take a HELOC on a US property and bring the cash to Mexico.

This may involve reviewing the lease agreement, consulting with legal counsel, and exploring potential negotiation options with the landlord or property management.

I know it's not an answer to your questions, but just an option if ever needed.

For some DSCR products the wait is 6 months, and for other usually awfully priced options are 3 months.Our way around this is funded a bridge loan with no waiting period for 75% of the improved value giving you cash out with our funds, then immediately refinancing that bridge loan into the conventional loan or DSCR product using the same appraisal is most cases.

The owner wants nothing but 275k for it, not open to any other options.

Adding this one as a potential option. 

Answering your question about my investing, I started 30 years ago with lease options, particularly with lease option assignments, (cooperative assignments). 

I know that you can loan an LLC money and then have the LLC pay it back later as an option.