When I put an anchor nest in my boat, I pounded on the thing for awhile to make it fit, but I was only shaping the bottom of the anchor.
Buy a #35 over the #30. I have the heavier one and really like it better. You still won't hold in fast water, but that would be dangerous anyway. You can hold anywhere it is safe enough to anchor with a #35. My buddy has a #30 and we are always coming off anchor, which freaks me out