First thing to do is check RIDE HEIGHT per Monaco specs.
Next, pull off one of the shocks and measure "compressed length" and "extended length". Then measure shock mounting point to mounting point with coach at proper ride height. At factory spec ride height, your shock mount dimension should be close to mid-way between compressed and extended length.
A "pulled apart" shock generally suggests that the shock is too short for your coach at its present ride height. A crushed shock generally suggests that the shock is too long.
Shocks are NOT designed as axle travel stops! Even the best can be pulled apart or crushed.
Could be something as simple as rear ride height too high, causing the axle to "hang by the shocks" over bumps. Which brings up the last point, IF the above has not identified the cause-- do you have axle stops in place-- can be straps or some other means of limiting axle travel on extension between axle and frame.