Edge Tamers (search edge tamer) for the front bucket work great, you can also use them in the summer to help from tearing up your lawn for any bucket work you might do where you have grass. I highly recommend them.
For snow "plowing" - At the start of the winter when hopefully you only get a couple inches of snow, spin your rear 3 point grading blade around 180 degrees and you will now be "grading" the snow rather than cutting or plowing it. If you can do that a couple of times you will hopefully get a nice frozen base established without removing any gravel from the drive. You can change the grading angle of the rear blade by adjusting the top link on your 3 point. You can also use your rear blade in this 180 degree rotated position for "grading" and smoothing your gravel driveway all summer long.
If you also have a front blade for the FEL, or a front blade for your tractor, putting a pipe (as mentioned in other posts) on the bottom cutting edge will solve all of your problems with "plowing" your gravel out of the driveway. The pipe stops the blade from "cutting". Call some of your local companies that sell snow plows for pickups and they can either get you a pipe of point you in the direction of who can. Quite a few commercial snow plow guys now use pipes on the cutting edge of their plows for gravel driveways. Once things get good and frozen, they remove the pipe.
I hope this helps.