BTW, I like your choice of thinner 3x3 SFC, I have toyed with that solution vs say 3x2, but never was able to get a good/acceptable method of tie in at the rear, front is no issue of course. Any close up pics of yours in the rear. I suspect there are wide differences in rear frames in this area, my cars i could get it to work out.
I have 3x3" sub frame connectors in my 72 Valiant....but I had to cut them through the floor on both sides in the area where the passenger would put their feet if the car had a back seat. I then welded the roll bar to the top connector where it is through the floor, to me this is the safest way to do it.
