Our 2007 PC2350 with 17,000 miles, the tire hoses are holding up perfectly, though admittedly all I do is add air. I have never disturbed any connections since new. I suspect the first time I touch them, I will have issues. I learned long ago that tire rotation is not worth it for motor homes.
On other RV forums, people use various varieties of these. The best kind is not an extender, but a valve that is shaped like this in the first place.
For such extenders, metal valves are required, not the standard rubber valves as cars have. This because the centrifical force from the weight of the extender will fatique the rubber stem over time. But I think motor homes all have metal valves to begin with because the PSI rating of rubber stems is not rated high enough for our application.