My coach is also built on the RR4R chassis. Let's hope you have the newer model of trailing arm installed on your coach. But if they are the original weak ones, I'd like to tell you my story, should you choose to learn from my experience.
My coach had 30,000 miles on it when I bought it from a dealer and the right side trailing arm broke at 33,000 miles. I don't know if the previous owner had done the recall because, at that time, Monaco was replacing the defective part with a new but identical defective part, so for all I know this could have been the second time a trailing arm broke on this coach. I knew something was wrong when, after a rough patch of gravel road, the coach started handling like it wanted to go all over the road, but it took me quite a few miles to figure out what was wrong.
I knew nothing of this trailing arm recall so I was fiddling with tire inflation, redistributing the weight, changing cruising speed, checking the air bags, etc, trying to get the coach back to the rock-steady handling I had before we hit that patch of gravel road, but all to no avail. In the end, I realized the coach was going down the road at an angle (airplane pilots call it crabbing), so that clued me in that the rear axle was not perpendicular with the center-line of the coach, so I pulled over asap and stuck my whole body under the rear axle and, after much searching, found the crack in the trailing arm where it was broken. The crack was hidden under the u-bolts that hold the axle to the trailing arm (see pictures).
Why it took me so long to figure out that the coach was crabbing down the road is a whole other story, but the short version is I had re-adjusted my mirrors (physically moved the arms out) at the campground just before we hit the gravel road, so I thought I had botched the mirror alignment vs wondering why my coach's rear end was not following properly.
Luckily for me my extended warranty covered the repair and they agreed to use the Source Engineering replacements, which are twice the size of the original Monaco trailing arms (see pictures in pdf documents below). This incident happened during our first month of full-timing so we had to wait 10 days for parts, in a small town in the middle of nowhere in Northern Ontario. Luckily for us, we were near a small town when I found the break, and the truck center doing the work was across the street from an RV Park so we had a place to stay while we waited. We were extremely lucky that the broken trailing arm didn't come out of the U bolts and let go of the axle completely. That would have been a whole different ending to this story.
It was while we waited for the parts that I Googled "broken trailing arms" and found (and joined) iRV2 - and found all this great help and information. I also downloaded these two documents:
More information is also available here on iRV2, from Source Engineering
(I think they were formerly Source Manufacturing
Sorry to have rambled on so long, but the take-aways are:
1. It's almost impossible to see the cracks on the trailing arms because they usually happen under the U-bolts that hold the axle to the trailing arms.
2. Having had the recall done is only postponing the inevitable, unless the trailing arms used were the newer upgraded model.
3. Murphy's Law says if they're going to break it will be at the worst possible place and time.
4. Peace of mind and increased safety are worth a few thousand dollars of parts and a few hours of shop labour (in my case, if memory serves, the insurance company paid ~$1500 in parts and ~5 hrs labour).
Hope this helps you make your decision.