Why not awnings over the bike path? This can be done in ways that look awesome and do not ruin the scenery and the view from the bike path. Thin film collectors in the form of tarps suspended from poles would make the installation cost commensurate with installing light poles. You'd need significant R&D in the aerodynamics, etc. However, you already need significant R&D for collector roadways, and you're starting out with an inherently disadvantaged design.