Can't you take the cover to a sign maker and have them put brass eyelets in it, like a shade cloth, then tie it down with rope?

I hope you were able to retrieve your cover with no damage.
I threw ropes over the entire structure on both ends and then later had to add a third in the middle.
I found I did have to re-tighten the ropes every now and then. I used the stretchy bungie cords and my rope was a little stretchy.
I didn't have the wind problem until around March/April. Just in time to take it off.

I have the cover on in a very windy site...had to make a few adjustments, but it seems quite stable now. What kind of clips did you use? I used Clipits at first, but they have to be used with a little duct tape. Even then, they occasionally popped off at first. I found some tarp anchors (search my "Pool cover makes a great sail" thread) that work very well with minor adjustments. Let me know if pics or other details would be helpful.

The clips have teeth - There was a picture on somones post. Home Depot .99
Duct tape may help to secure better to cover.
Will try agin with more rope!
I have a double poly house- It is very slippy - maybe that is the problem

I may try this at Home D - I could attach and even reinforce with duct tape.

Here is a link that might be useful: Gormmet

Here is a link with the picture.

I found that what you have to do with the tarp anchors is wrap the edge of the cover around a toothpick or a twig parallel to the edge, then clamp the whole thing in the tarp anchor. The toothpick, place in the anchor behind the teeth, keeps the edge from sliding through the teeth. It is stronger than Clipit and lots easier to get on and off. Another way to do is is to tape the toothpick or twig parallel to the cover edge with duct tape and put the clamp on the duct tape. SB

Here is a link that might be useful: First solar pool cover sail link

Here is what I just did-
At each end I took rope and folded the solar cover over the rope -then duct taped the folded end. The flap is tightly secured with the tape and the rope holds down each corner.

I will use additional rope - to secure the sides and end crossing many times. Many more that i originally had.
I thought an old Soccer net would be great - - still looking - rope will do for now.
Let you know when the wind comes again. Will also try your idea with the twig-

Here is the north side of my GH:

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Here is a pic of the twig technique:

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Robert, it looks as snug as a bug in a rug. You did a very neat job. So the twig just gives the slippery cover something to grip on. Neat idea.
If you continue to have wind getting under the cover you may could seal it down with duct tape. No not the regular gray stuff. They now make an 'All weather' tape. It is gray also. They have clear but I couldn't find it in 'All Weather'. It was cheaper than ordering the clear 'greenhouse' tape from the internet. 30 Yards was around $5. @ Wal-mart. That's 90 ft.
I wished I had done like you and put my vents in the knee wall. But I had intended for my vents to be in the back wall not the front wall and have the exhaust fans on the front wall. But my DH and the installer got them backwards and I just let it go. The air coming in would have been from the North and probally cooler. Now it's pulling the SE air which is hotter. I have bought some extra vents that can fit in the exact space as a cement block but not installed yet.