But of course!
Over at The Crafty Wench, I found a suggestion to move sleeve increases/decreases in one stitch from the selvedge on a RS row, and in two stitches on the WS, thus eliminating the lumpy sleeve seam problem I complained about. Ooof. This is one of those things that seems so glaringly obvious once somebody says it, yet it probably would have taken me two or three more sweaters to get there on my own. Thanks, Crafty Wench!