Bell washer replacement

Maybe there are some tips out there, maybe I have the only solution. I have a 2007 Antiqua that has many broken bell washers. These are the white plastic washers under the bunks (outside) that the bungees loop over to secure the canvas. I bought all new bell washers from StarCraft and experimented with replacing one and was unhappy with the test. I drilled out the rivet with a 1/8" bit but strangely to me, the hole "wallowed" out to about 3/16". My plan for that one is to epoxy a dowel into that oversized hole then screw the new washer into place. Are there any tricks to making this less painful? StarCraft did not really help. They just said "yep, drill out the old rivets". I've drilled out many pop rivets on other projects but never had this much trouble.