A few RV/Trailer Frame manufacturers have said (or implied) that they will void the warranty on their 5th Wheel (or frame) if an adapter is used for hooking up. 

Officially, that is illegal. According to the FTC’s Magnuson-Moss Warranty Act they can only void the warranty if the adapter actually CAUSES damage, not simply if it is USED. Additionally they have to PROVE the damage was caused by the adapter.

Our solution:

For the Ultimate 5th Wheel Connection, if they won't cover it, please submit a claim to customerservice@anderseninc.com. We stand behind our product and with the Ultimate Connection we will cover warranties up to $5,000,000. For more info regarding this coverage, see our supplemental warranty.