My first "RV" was a '72 Scotty Hilander TT. I used Rene's blue tarp, but I used loops of paracord in the grommets and slid the knots of paracord into the track on the trailer. Got some extendible poles from an old canopy and used at the outer corners with guy ropes. Unfortunately, the only pics that remain of that Scotty don't show it with the awning deployed.
Side note, try an RV salvage yard or repair shop and see if you could find a second hand manual A&E that somebody replaced with an electric awning. I know the shop I use in N. Arkansas has several laying around he'd probably sell cheap.