I believe several university Ag Extension Services have published truss designs for clear span buildings, but you'd still likely want a PE to give it a look over, as their loads and spacing are likely based on agricultural outbuilding design (much lower design values). Truss design is very detailed as there's a lot more to consider than simple loads, and you want to build/assemble the trusses exactly per the design guidelines.
7' of overhang adds an additional level of complexity, as the forces have to be either supported from the end of the truss or cantilevered back to the main structure. I think in residential construction we're allowed 3' of overhang without any outside support. Anything further requires an engineered solution.
Just some thoughts, as we all want Sid to be safe hanging out at the dock! Look forward to seeing the finished project!