Exactly, like in the old days when guys used fence post for their cages.
The rules are there because we can be idiots.
If you're going to build the firewall, do it right.
Fence post??? That's sounds kinda high end compared to some of the stuff I have seen. A lot of cars in the 70's including a few very prominent pro stock cars had roll cages made out of stick welded black pipe. That old SRD race cars 70 Camaro that I own has a black pipe cage. When I talked to Richie Zul about Grumpy's 70 Camaro when he had SRD build it,he said it had a black pipe roll cage too!