Okay, so Dometic sent me a DMR702LB parts manual, which is what I posted above. In working with my dealer, they have a current DMR702 manual which indicates the trim piece is part number 385151601.
Both the DMR702 and DMR702LB have the same product number, so I'm not sure what, if any, difference there is in the two trim part numbers. Color perhaps?
2015 Rockwood Signature 8329SS
2015 F-250 XLT 6.2 gas