As the original poster, I wanted to follow up for anyone reading this thread in the future. Since installing the reinforced snap-up brackets last August, we have made 6 more trips of varying distances and have not had any more problems with the brackets. For us, and our configuration, the reinforced brackets seem to have 'done the trick'. Hope this is helpful for others...lots of good information here from all the other posters too!
Roger & Dawn M.
2011 Rockwood Signature UltraLite 8315BSS
2004 Ford Excursion
Nights camped in 2011: 27
Nights camped in 2012: 34