I've never heard of an "approved owner repair" on any Keystone trailer that resulted in a voided warranty issue... That said, I have seen (and heard about) a large number of "hey, I can fix this" issues, where an owner went out on a limb to tear stuff apart, couldn't get it to work and hauled the pieces to a dealership requesting a "warranty replacement" only to be told, "You broke it and the warranty doesn't apply"....
To me, it's more a matter of "common sense" than it is a matter of "unscrupulous Keystone trying to screw its customers"....
I can very well relate to "owner fixes that aren't quite right"... I remember buying a coocoo clock in Germany, got it home, the music box part didn't work properly, so I took it apart one night, after several Bitburger Pils (probably just enough for the self induced courage to kick in) and "fixed it".... I had about 3 or 4 "extra screws" and a "spare gear" when I got it back together. It's still hanging on our wall, I wind it weekly and it's still working to keep time, after 50 years... But the music box didn't work when we bought it and it's still "like new and not working half a century later".... Herr Schleigh, at the coocoo clock shop in Trier took one look at the clock's pieces and told me it would cost more to fix it than to buy a new one, so he "voided my warranty" (if there even was one) based on me and what I did, not on whether there's a "government program to protect owners". Looks like not much has changed in the last 50 years... YMMV
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS