While the rest of us toil and sweat to pay off the mortgage, the folks at Swallow Hill Music Hall came up with a better idea: make it fun. So, this summer they organized a pair of leisurely floats down the Gunnison River, with gourmet camp vittles and music to match: The first, which embarked last weekend, featured zen cowboy and songwriter extraordinaire Chuck Pyle at the entertainment helm; the second, scheduled for August, features poetic cowpoke-type Roz Brown. Proceeds go into Swallow Hill's mortgage kitty. What a great way to stay afloat.