trucks and roll cage /bar rules

[jeff swisher]

I have a 1947 dodge truck and i will be building an internal cage ,it will have bars passing through the fire wall and curve down attaching to the frame in the front ..
My question is.... when are you required to have the bars exit out of the cab and attach to the rear frame? As i do not want to put those in and ruin the looks ...And they get in the way of my fishing gear
This will be mild steel 1 5/8'' seamless DOM That is another question I always use that DOM .125 wall ...I have seen people use cheaper seam type tubing is that legal? I do not think it is legal or safe, my 2 cents