Catalytic converter and muffler replacement questions

Hey All,

I have an '02 SE CC LB that has been throwing a P0420 for the past 4 - 5 years, and I'd been getting away with it in Georgia by resetting the ECU, driving 100 miles to the emissions testing place, and then the light would come back on around 102 miles. This method got worse with each year, and last year, I had to do the reset, use premium gas, and a couple rounds of intake cleaner before it worked. I had replaced all but one oxygen sensor a few years back (rear passenger, super stuck), but that didn't help the issue, so this year I decided to replace all the cats and the muffler. I went all Magnaflow. The drivers side was tough, but not really difficult and I've got those two cats and the muffler in place. The passenger side is starting to look impossible. I've got the two bolts from the rear cat to the Y pipe off, but only 2 of the 3 from the front cat to rear cat (still can't get that O2 sensor off, will probably just destroy it) and the manifold to front cat bolts are covered in a seemingly endless amount of heat shielding. My first question is, if you can remember doing it, what all had to be done to get the passenger side front cat out?

Second question is in regards to the Magnaflow muffler. The muffler looks like it was expecting two hangers, but my truck only has one. This muffler is a bit heavier than the OEM one. Should I get another hanger or will it be ok once I get everything bolted and tightened up?