Report: These work. Recommended.

I tried the Brighter 1157HP bulbs from Candlepower. They are rated at 14/50CP. These are specifically intended for Stop/Tail lights. I've got about 5K miles on them (mostly highway) and they are working great.

I can tell that they are brighter. My cups have fresh aluminum paint in them, so your mileage may vary.

My truck tends to run up at about 14.9 volts for longer than most, due to cold temperatures. So high volts should not worry you. I have not run them at really high ambient temperature, so someone in Phoenix may have to check and see if there is any problem with getting the plastic bezel too hot. Not likely, but a concern for desert guys, at 115F.

 

Still no problems in Summer.