If you do this, you could make the weights removable, which would allow you to adjust the weight if 35 pounds ends up being too much, and it would make washing easier. The pellets could be sewn into little packets that could be removed from the pockets.

I should add that I don't know anything about this type of quilt, so you might want to keep that in mind when considering my advice. I don't know if buttons/snaps/zippers to keep the pockets closed would cause any kinds of problems for the user.