In addition to the RR4R trailing-arm fix mentioned, Source Engineering offers a "Ride Enhancement Kit" for the RR4R. No recommendation one way or the other, as I don't have an RR4R coach.
Monacos and HRs of that period are prone to slide floor rot, especially at the outboard, forward edge of the driver-side slide. This can be found and repaired. One popular product to apply to prevent further problems is called "Guardian Plates."
My HR, and many like it from the same era, has clearcoat failure that causes the paint underneath to break down. You usually find evidence of this at the upper edges of the front and rear caps. Repair means a do-it-yourself or, in my case, a session at the paint shop. Other manufacturers have also seen clearcoat failures.
On any coach of its age, look for evidence of water intrusion at the ceiling, above and below the front windows (including the floor), and around the walls and floor adjacent to the slides.
This past Summer I spent a lot of time repairing a problem along the horizontal joint between roof and sidewall, on the passenger side. The problem occurs on some Monaco and HR coaches. It was not fun to fix. Unhappily, it is also difficult to detect, until a water leak occurs.
2008 Holiday Rambler Admiral 30PDD (Ford F-53 chassis)
2009 Honda Fit Sport