Seven years ago, Joan Wells and her husband Mike left San Francisco and a nine-to-five history for 160 acres in the Oregon Rockies, and their recalled hard-scrabbling may turn up as required reading for others country-bound. The work was more than they'd envisioned, the isolation sometimes perilous, and they're still considered strangers by the neighbors who believe ""Trees are there to be cut."" But what they've gained, besides a tumbledown two-rooms and a doorless outhouse, are the incomparable pleasures that all those city-worn dreamers are seeking: free-roaming ducks and chickens, fresh goat milk for breakfast, deer grazing in the vegetable garden--the whole arcadian kit and caboodle. We ""hadn't meant to take the sub of subsistence so literally,"" she insists. ""There are times when one must say to the esthetic and pioneer spirit, 'Bug off.'"" They have to make elaborate arrangements to go off for a day, and Mike, contrary to early pledges, had to use a .22 to trim the porcupine population. But the compensations are immeasurable. ""In silence and isolation, I have found a self I never suspected. Thrown together on this inland island, we find, over time, one another."" A plucky, warming book.