First off you don't need to take off the exhaust..
Remove the right rear wheel, put it on a jackstand rather than the factory jack for safety though, then get in there with a wrench and go to town. After you get it in about half way then you can put a socket and breaker bar on it, that's how i did it. Never messed with the exhaust. Took some extra time but i didn't want to take anything else apart to put something together.
As for the bolts... After the posts earlier today i made a phone call myself, just got home and a chance to post tonight. Those bolts, 8.8, come with just about every hitch out there. A friend of mine, whom i called, works for U-Haul and they put on hundreds of hitches per year. I asked him if they ever heard of a broken bolt on the hitch due to it being an 8.8, he said NO.. According to him something else bends or breaks before those bolts do. He did tell me about a story where a tow truck tried to recover a truck in the ditch by wrapping tow straps around its hitch tube, the tube bent, and the brackets bent, and one of the welds on the tube to the bracket cracked, but the bolts didn't break and they were 8.8, he also mentioned one case where he saw the captive nuts pulled out of the frame, bolts still intact.
I used the grade of bolts that came with my hitch. Curt, Reese, Hitch-Rite, you name it, they all use the same bolts and they sell thousands of units a year. Is it possible to break one?? Yes... Am i going to loose sleep over it?? No...
If something goes horribly wrong enough to break one of those bolts i got worse problems, like my trailer getting rear ended by a semi tractor, or rolling it into the ditch with a trailer attached, etc.
FYI, the bolts holding the skid plates are NOT that heavy of a grade. There was a long drawn out discussion about those bolts on LOST, i did some searching, where a guy was wanting to install some skids he bought and asked about what type of bolts to use. One guy went and bought bolts from a dealer and they were LESS THAN grade 8 according to a hardness test.
Use the ones that come with the hitch, if you don't your hitch warranty is no good either.