They usually rent them out the entire ski season to the same renters from Manhattan and they tell me that the income covers their year round mortgage and maintenance costs.

However, your landlord is likely notifying you of  the complaint because there are sufficient complaints from her other tenants to warrant letting you know; concerned that other good, quiet tenants may leave if the issue is not resolved; and covering herself in case there is an actual drug issue. 

I recently learned that the safest seconds are those where the first is performing, and there is enough equity to cover both the first and second position.

It covers not only my rentals but also things like car accidents. 

That way you know that you are covered.  

In my experience most properties with structural issues are not discounted adequately to cover the cost to correctly remedy the problem(s). 

It is not an issue to borrow money to pay the loan, however, your mortgage broker may have an issue with you not have the necessary cash to cover any unexpected issues for a few months. 

I don’t have cash but I know I can get approved for a line of credit that would cover my down payment.

Will the deposit cover the unpaid balances, cleaning, and repairs?

That way your mortgage will most likely be completely covered and you can live there for free.