Payoff advice needed

[T Pellin]

Hoping to pick your brains about the best course of action here.

$135,000 remaining on Primary home @ 3.75%

$165,000 remaining on Investment property @ 4.25%

Both properties are in North Carolina.  

Investment property is a beach home and used for vacation rentals (so, cyclical income that we mostly have to dump back into upkeep and insurance). Most importantly, the investment property will become our primary home upon our retirement in 14 years.  In retirement, our monthly cash flow will be cut roughly in half, which will be no problem if we eliminate both mortgages by/at retirement.  Retirement is guaranteed pension, not 401K etc.  Savings is currently at 85K.

Which makes most sense to achieve this goal?

Do we:

1 - Pay off the current primary home with the lower balance and interest rate asap and then pay down the debt on our investment/future primary home until retirement, and then take the proceeds from the sale of our current house and pay off the remainder of the new primary (former investment) home and live free and clear for our retirement, making the cut-in-half cash flow just fine. The income from the home sale would be used to pad our retirement savings.  

2 - Pay down the investment property with the higher balance and higher interest rate ASAP and then use the primary home sale to pay off the remainder of the primary home mortgage, whose balance will be minimal by that point, and then use the cash for retirement as in #1.

2 - Just pay the minimums on both for the next 14 years and then use the primary home sale to hopefully finish off the investment-turned-primary home mortgage.  The cash we would be saving (bank account only, not invested) from not paying extra on the mortgages(s) would be our retirement cushion instead of the cushion mentioned in #1.  

Things to consider: We are 14 years from retirement, with 2 kids in elementary school.  Having a strong cash safety net is very important to us in case of job loss, critical illness, etc.  Also, even though we know that high leverage is good for investments and taxes, etc, our current goal is to have no mortgage costs at retirement, so we'd like to stick to that plan.  Our mental health will just be better if we know we can 100% make it on just our pension money.