On the cheap, plastic covers/diffusers from ordinary household led light bulbs are a great fit on the bezel with usually minimal size adjustment on the inner rim. Could line the inside or outside of the cover with aluminum tape or something else to black out a portion. Perhaps cutting a disc from thin translucent plastic sheet would be enough diffusion although it wouldn’t get you 160°…still might soften everything enough to be effective. The smooth side of milk milk jugs, craft pp sheets, etc. There are sheets inside of some led monitors and TVs that might be suitable if you have junkers to part out (although some of the sheets are a bit thick). I’ve found the light bulb covers to be very pleasant and useful but I don’t care about the 280°-ish emission because that works great for how I tend to use it.