Other than a full modern roll cage, as fitted to racing & rally cars today, most of this stuff is a cosmetic joke, or worse.
I did the last ever LeMans start sports car race ay Bathurst in 1964. 40 drivers raced across the track, leapt into their cars, & dashed off for 6 laps of a much more dangerous track than is Bathurst today, most of it bounded by trees & barb wire fences.
You know, in those 40 cars there was not a single rollover bar or seat belt to be seen. Would you believe, we all survived.
I have seen a Lotus 20, & a Lotus 19 turned over, the 20 at very slow speed. Both were fitted with fully welded approved rollover bars. Both those bars contributed to killing the driver. I have no doubt that most after market rollover "protection" fitted to cars like ours are of similar value.