1)The Sandy Hook, Aurora, Clackamas shooters and the like needed a way to transport themselves and their firearms to their targeted location. There would of been no way they would have been able to walk around in public carrying longarms without attracting attention. So perhaps mental screenings during the process for the Driver's license or State ID might be a viable solution. The 2nd Amendment isn't affected and the anti-gun people share the same pain.
No way? How about any number of purpose built longarm cases/bags or any cases/bags that a long arm would fit in?
A single comprehensive mental health screening at the time of obtaining and/or renewing a license would not only be extremely expensive(who's going to pay for it?) but extremely intrusive and time consuming.
Not to mention, what about all the people who don't have licenses? If someone is plotting mass murder, suddenly the line is drawn at them stealing an illegally operating a vehicle to get to their target?
This idea is about as valid as suggesting periodic mandatory mental health screenings for all people...