Last year I upgraded my trailer lights, installing LED pipe-lights and the little dome lights on top of the posts. I could not be happier with the pipe-lights, it is the guide post lights on top that I am having trouble with. When they work they are great as they help in backing at night, etc… but, I can’t keep bulbs working but for a month or so. They do not look burned/blown out, rather the filament just looks broken. Could they be breaking while moving (the posts do wiggle while moving) and, is there such a thing as heavy duty type 90 bulbs? Of course now I see the same company now makes LED dome lights. Makes me wonder if others were having the same problem.
Did it keep doing it in warm weather? Cold Weather kills filaments that vibrate.
Hold the tomato, fool!
Replace 'em with led’s- too much vibration.
Does not seem to be any one kind of weather. I will probably just end up replacing the entire unit with LED’s.
bust it open and look at the lights…you can get LED’s that plug into most standard 12V sockets. West marine’s got em, but you can find em cheaper other places. ive seen em at auto zone before.
I fought the same prob all winter and spring, and those bulbs aren’t cheap. I loved the extra light backing in during duck season, but I finally stopped replacing the bulbs. 
DRIVE IT LIKE YOU STOLE IT!!!
The harder you work, the luckier you’ll get.
I found some pretty cool LED replacement bulbs on the internet but they were too tall to fit in the existing lights (the red/amber dome would not go on over them.