We have the original stainless braided rear wheel valve extenders on our 2007. No leaks so far in 11 years but I never disturbed them. I will be replacing the original tires soon and possibly switching 4 of the 6 wheels to alloy. For the rear wheels, I want to install solid formed extended stems, not stem extenders added to short stems. They resemble what you would see on 18 wheel rigs. I can't find the supplier right now. I recall finding only one source offers them for the E-series dual rear tires. They are expensive but feel they are worth the cost. With 2 alloy outer rims and 2 steel inner rims in back, the extended rear stems need to accommodate both the thinner steel and possibly thicker alloy.
For PC owners who just want to change their stems.....
Tire shops with the right tire machine can change valve stems without completely removing the tires from the wheels. They break the front bead and with a special arm on the tire machine, press down the front of the tire to expose the stem area to swap stems. Doing so does not affect the balance of the tire. I speak from experience replacing tire sensors and valve stems on typical vehicles. I am a non-certified mechanic, volunteering at a non-profit.