Okay, first off thanks for all of the info and advise. I have done a ton of research over the last 24 hours.
I called Briggs and Stratton 2 times and the unit I am looking at definitely has a approved spark arrestor. In fact it is geared / marked towards RV camping. (it has a specific dedicated RV 30 amp plug, separate 30 amp breaker and it even has a different muffler designed to be a bit more quieter.) There is even a video which shows how to replace the spark arrestor if needed.
There is a government publication that address noise level in campgrounds, but it concludes that there is no longer a major issue associated with generators anymore and that a specific noise standard is NOT preferred and that there should NOT be a "standard" noise level established for generators. Here is the link...http://www.fs.fed.us/t-d/pubs/pdfimage/92231301.pdf
Next, I called Yellowstone and spoke to a senior ranger and I explained everything I was trying to do, what I was looking to buy and etc. She laughed a little when I started talking about the DB levels of generators..."well, I can assure you that we don't go around with DB meters in our trucks testing generators" She, told me generators were not near the problem they used to be...even the so called "construction" style. She told me if it were here she would buy the much less expensive Briggs and Stratton and that it would NOT be a problem. I thanked here for her time and advise...asked a few more unrelated questions and that was it.
That is what I am going to do...buy this newer model Briggs unit that is made for RV camping and save a lot of money.
I do appreciate everyone's help...I certainly know more about generators than I ever thought I would...