A redundant PRV system would negate the need for a scatter shield. Rupture discs like OP mentioned are a great back up.
(No need to contain an explosion if an explosion can't happen)
An FMEA (Failure Modes and Effects Analysis) would be a good start.
I agree with MG on this. I am all for a rupture disc or additional blow off valve to protect against run away C02. If its in the top of the tank it will only shoot out Co2 and fuel vapors. If the seam fails with scatter shield you have all your fuel coming out.
The Red head seems to be less of an issue. As there have not been many failures and most of the issues have again been user error. same things happened with our dump cans with Red heads. if not in and out correctly they can get stuck or leak.