There's a custom bike shop in town that has a fully-adjustable trainer with power meter. He starts by setting the correct crank length (.21-.216 * leg length crotch to foot), then adjusts positioning for maximum power/comfort. Every person I've met who bought a bike from him has said the same thing: the fit was PERFECT the moment I swung a leg over the bike. I regret not consulting him before we bought our tandem last year.