I love cool RV gadgets, upgrades, mods and things that make RV-ing more fun and easier. The bumper mount grill isn't one of them. Had a close look at one at a recent RV show and can see more negatives than positives. Odors & smoke can be an issue with open doors and windows too.
Our Weber Q on a picnic table or folding table works great and we have a 20' hose to a quick connect under the trailer. I like the look of a clean bumper with nothing on it. We have a BAL spare tire carrier now and the rear looks much better.