Rember cars of the late 80's early 90's. They weighed nothing, had fuel injection, just enough power to go highway speeds and got 40+ mileage.
My faviorite car is a 91 metro. Easy to work on, nothing you don't need, and light. But far from safe.
I grew up in a body shop. Seeing what works and what does not.
A FR car has a few disadvantages. unlike a fwd car it can not spread its engine and transmission across the front to act as crash barrier. A FR also has the added weight of a crossmember, driveshaft , and rear axle or at very least a diff.
Suspension tends to be heavier as it needs to cover all four corners better then in a fwd where the rear is dead.
You generally have greater twisting forces in a FR layout. So the same weight unibody as a FF will tear when used with FR(bmw).
Biggest thing is crash "protection". A fender to fender hit is the worst kind of accident you can get in. Airbag, curtains, and padding don't do much when your head slides off the bag and strikes the door glass. Or when the tire is pushed back against the firewall pinning your ankles in the car.
With a FF you have suspension and A arms which generally remain stock. With a FR people will want to lighten the A arms so more bracing is used in the fender areas.
If you want light and safe you need a monocoque frame. The downside is no crush zones so safety equipment such as belts, seating, neck brace, helmet,
etc becomes what stops your momentum.
End of the day anything above 40 your risking a injury depending on where the strike is.
I have been in over a dozen accidents. All myself usually involving a winding country road or a large hill, excessive speed, a loss of traction or landing wrong.
When you get into that moment when you realize you pushed it a bit to hard you will be glad you have that weight. That being said chargers are not terribly safe from the dealership. If you plan on doing something fun a "family" cage or even adding foam might be the diffrence between a bruise and a break.
Dont be concerned with the weight. That just gives you an excuse to add more power.