Wow, Im glad you figured it out.
Your RV only has 15K on it .....and the Cat is plugged?
Did you ask them what could have caused the Cat to plug up in the first please.
Might be something else wrong in addition to the Cat that cause it to clog up at such low miles??
Burning oil? Running rich? Bad fuel? Ebola?
I dont know just thowing things out there to see what sticks.
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, Fresh water surge tank, Black Tank Tornado flush, 4999 zip ties.