Not for sure, but in the past pretty much any time you strike an arc on the frame, bumper etc, you void at least the frame warranty. I think I've voided every one of them, but never had any frame issues where warranty was needed. I've always built my own receiver hitches to tow the boat, or haul bikes. The Jay Flight has the factory lippert hitch, but it will be getting beefed up as well since 6 stitch welds doesn't satisfy me. If I have frame issues, I'll probably fix myself anyway. You mention bracing the bumper. Do like I did on a previous one. Cut the whole thing off and but new box tubing from the frame and 4" square tubing. Way thicker stronger steel, yet still looked stock. Receiver hitch was welded directly to the frame, and the new bumper.
John and Rebecca Dickson
Emma-8 / Little John-5 / Iva-1+
2013 Ford F-350 Lariat FX4, CC LB PSD, DRW
2015 Jayco Jay Flight 28BHBE (#8)