Do you have any credit cards with a 0% balance transfer that has a 3% fee?
Is the credit line large enough for your summer needs?
Often those offers allow you to write a check to yourself or deposit the money into your bank. You don't usually have just a one and one chance, but they allow you to to more 'balance transfers' over the whole special fee periods.
Often the offer is either 3% up front fee on the amount or 5% interest on any amount still outstanding. Total due by 12, 15 or 18 months, before interest rate going up to usual 18-24%.
The 5% offer, if you have one and can tap it, would work well for you.