This is in your 07 Coachman?
7 plus yrs old water heater......so have you been routinely clean/flushing tank?
Mineral build up inside tank and on electric heat element will reduce heat transfer capabilities.
Also......is water actually heating to full t-stat set point?
T-stat ever been changed?
Is it tight against tank wall....making contact with a clean surface?
Which Brand/Model Of water heater?
Does it provide adequate hot water on just propane?
With combo (electric & gas) both can be used at same time for faster recovery time>>>>>>not a cure just a work around until you check out element, t-stat and actual temp of water (at PRV----------CAUTION water should be hot like 130*F-140*F)