front body support, floor pan, etc

[tp85]

In preparation for building a roll cage, I decided to replace the rusted floor pans on my 72 blazer. After removing most of the floor in front of the seats and near the rocker panel, I found the following:

front body support rusted (the half near the door is gone)
front door pillar badly rusted where front body support connects
no inner rocker panel (outer had been replaced, but they neglected the inner)
rocker box has interior surface rust (future POR-15 job)
rear door pillar rusted at very bottom near rear end of rocker box

Has anyone replaced the front body supports? Does anyone have pictures of how the front body support connects to the bottom of the front door pillar (just under the kick panel)? Can I replace the support without removing the rocker box? There are four bolts/nuts in this area, and I wonder if these connected the body support to the front door pillar?

How critical is the inner rocker panel to the body strength? I'm trying to decide if I want to rip off the outer rocker panel (which looks pretty good as is).

Also looking for pictures of the rear pillar near the back end of the rocker box? There are two bolts/nuts in this area.

Anybody paint/repair their rocker boxes while still on the truck? Seems like the rocker box interior is accessable since much of the floor is removed.

I want to do this job correctly, and not cut any corners. I am mainly concerned about the structural strength of the body (since I don't use a hardtop), and stopping any existing rust from continuing to eat away my truck. Any pictures, advice, or links would be great.
Thanks.

Tom
72 K5 Ochre 250