As a reply/suggestion to my own question --
Now that I have shopped around abd bought a cover, I thought I would share my experience and ideas. I found and bought a tarp at Lowes for about $60. It is one of those ultrathick tarps with a supposedly very high UV protection factor. It is gray/silver on one side (this side is supposed to offer the most reflection and thus should be outward to reflect the sun). I leave my mast on the mast stand, so I needed a larger size tarp in order to be able to completely cover the entire mast and boat. Plus I wanted to keep the tires/wheels on my trailer out of sunlight in order to lengthen their life. I think mine is a 20'x30' tarp. It's too big, but, again, I wanted everything totally covered.
So, for about $60 (or less), this is a good idea. Not the prettiest solution, especially if you keep the boat at home outside. But, it should keep the boat out of the elements pretty well.