Lingonberry, blueberry, and cranberry come to mind. ;^) Checkerberry (wintergreen) too.
Give them more light (cut down enough spruce/fir to make some sun on the spot) and fruiting should improve. Or move the plants to the sunny spot.
Potatoes actually like a light, acid soil pretty well, though they would probably appreciate more nitrogen than there probably is. They can approximate perennial in zone 4/5, or at least I haven't planted any for 3 years and they keep coming back, even after I've tried to dig them all out!
Apples tolerate somewhat acid soil fairly well, but blueberry levels of acid might be a bit much - still, you could lime their area (and not the berry patch) initially and in your yearly maintenance. But YOU might not get much food from them if you are only there one week in summer - perhaps with an extreme summer apple like yellow transparent.
Rosa Rugosa is both hardy and relatively carefree, but again, the rose hips might be a bit late to do you any good in summer.
Garlic is a possibility - left to itself it does tend to shrink year to year, but if you dig it up and replant cloves in the "summer maintenance" it could work out. While common practice is to delay replanting, many folks do just replant when harvesting, and it's certainly disease and deer resistant. It would also appreciate a hearty dose of lime to get the soil near-neutral in its spot.