I've always thought enduro (laydown) side tanks are a dumb idea from an impact standpoint. Modern fuel cells are available.
I'm pretty sure this would fit the bill for most, and could be tucked somewhere safe --
https://quartermax.com/4-gallon-econo-rail-fuel-cell/
For the first incident, I'm not even sure it was a laydown...not much has been reported. I feel the orgs owe it to the racers to have a thorough analysis and discussion of any neccesary rule changes (including the sometimes wise choice to do nothing because of the law of unintended consequences..._
But I've never heard what lead to the original incident happening, what actually happened, or what the response time and type was... The risk of death from 80% burn coverage is high due to secondary infection. I'm glad that his family got some extra time with him, but sad the incident occurred at all... Nomex is fire"proof", but not abrasion resistent. Cordura is abrasion resistant but melts... Nobody makes a dual suit, but OMP used to. I've thought about marketing one. At the least, one could wear nomex underwear under a cordura suit... Hot, but not 1400° hot.
Regarding the 2nd incident, I am forced to report 2nd hand as I wasn't there to witness it, but seemed to be a combination of several factors:
1- Improper attachment of the most important piece of safety gear (helmet)
2 - a cross-wise kart after the crest of a blind turn leading to a t-bone type crash
3 - mixed classes with high speed differentials leading to the incident (though a stalled cross-wise kart is the worst type of speed differential...)
My friends surmised that It may have been a survivable impact had the racer been younger and had the requisite safety gear still on their person.
Life flight was called, but he was declared dead at the scene. RIP racer....he was a good man and dedicated volunteer to the sport. But it's a sober reminder that nothing can be taken for granted.
Let's face it...when you get about 60 mph on a kart, the wrecks are less survivable. The human body wasn't made to take sudden stops into fixed objects. Most of us know and accept the risks, and for my part, I try to minimize danger exposure on my own equipment where possible, above and beyond the orgs requirements sometimes.
At least roadracing requires some sort of licensing. Your local dirt unlimited class or sprint racing? Not so much...