Weight is only one problem. There are many others.
The big monkey in the room which nobody has mentioned is cooling. I've seen people do this and have all sorts of cooling problems. You start blocking off 40, 50, 60% of your grill area and you are going to have cooling problems.
Ford does not even recommend putting a screen in front of their EB intercooler because of air flow problems. Yes, yes, yes I know, we are not talking about an EB, but this will give you an idea if a small screen can cause problems what do you think a full size bike can do to a cooling system?
Good luck with your project, but I would never do this.