Trailer Straps

The cover that came with my boat has loops in it where straps would go through, but no actual straps. It is a very nice sunbrella tow cover that fits around the bow crash pads and everything- I just need straps for it. It does have a drawstring, but obviously that's not enough to tow with. I leave the boat in the garage so I haven't really had to use the cover, but I would like to have the straps in case I have to tow in the rain. I don't want to have to take the boat and cover to a shop to have it fitted with straps in the middle of the summer- does anyone know of a cheap, easy strap solution (say, one step above bungee cords)? Knowing this group, there's some hardware part that happens to be an ideal strap...

I use a continuous cotton clothes line, takes a little longer to install however it will not scratch the hull or the trailer, I feed it starting from the bow and work around the entire boat back to the bow.
I only trial a couple times a year and usually long distance, may not be this best solution if you are towing often.