Why don't you just use the original oval one again?. It will at least stop stones punching holes in the filter. I still use my original oval one even with a larger stage 4 type filter.
Round one is the go, keep most of the rain and debris out, I took mine off and put one of them SE front facing things in an attempt to get a bit more knee room, it did but then you gotta/should have a sock cause they don't like a big downpour, wide glide used to have a fit everytime it happened to it, funny though we talked about this some years back and a few blokes reckoned they never had an issue, beats me.
if the rain sock is great for rain, or even dust, why not just leave it on all the time, if it makes no difference why bother
Its only water! Its not going to combust or lean out the fuel air mix. It will cool the intake charge though which is a good thing.