flu, I take it you currently have a conforming loan? In light of your circumstances I think you are very wise to keep your 15-yr loan term and endeavor to pay it off in 10 yrs.
Is the new $2800+ mo amount PITI or just PI? I’m not too familiar with the rents up there but if your payment is just PI, I don’t see the viability of renting out without either a negative cash flow or the hassles of turnover with a rent set at above $3500 mo.
If you pay the extra every month like you are planning to for at least a couple of years, your new 15-year loan will begin to amortize very quickly at about 40-42 months in. This will give you and your family a lot of flexibility.