put a 3inch riser on my sled earlier this year and angled the bars up a bit more so it's closer to a 4. cover did not stand a chance to fit. what we ended up doing was stitching some old denim (off of some jeans) to the gas cap zipper flap thing. then with the gas cap flap, i put it over one end of the bars, move it down to the skinniest part of the post and then slide the other side over the other end of the bar. the denim flap is used to help not allow air in, it's just more material i can use to wrap up with a tie strap. its leaves the bars exposed but they stay clean.
if you want i'll take some pics.